In dmesg i see a lot of errors related to cd/dvd drive. Not sure what this is about.
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 Sense Key : Not Ready [current]
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 Add. Sense: Medium not present - tray closed
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 12:45:39 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 3 prio class 2
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 unaligned transfer
Jun 18 12:45:39 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 unaligned transfer
Jun 18 12:45:39 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#16 unaligned transfer
Jun 18 12:45:39 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#17 unaligned transfer
Jun 18 12:45:39 Main-I5-Linux kernel: I/O error, dev sr0, sector 6 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 12:45:39 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 13:08:06 Main-I5-Linux kernel: tun: Universal TUN/TAP device driver, 1.6
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 Sense Key : Not Ready [current]
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 Add. Sense: Medium not present - tray closed
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 13:31:11 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 unaligned transfer
Jun 18 13:31:11 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#16 unaligned transfer
Jun 18 13:31:11 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#17 unaligned transfer
Jun 18 13:31:11 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#18 unaligned transfer
Jun 18 13:31:11 Main-I5-Linux kernel: I/O error, dev sr0, sector 6 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 13:31:11 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 14:56:29 Main-I5-Linux kernel: kdenlive_render[26777]: segfault at 4 ip 00007fddd8b57584 sp 00007ffcb13cdb48 error 4 in libQt5DBus.so.5.15.9[7fddd8b3f000+4f000] likely on CPU 0 (core 0, socket 0)
Jun 18 14:56:29 Main-I5-Linux kernel: Code: 55 70 49 89 e9 49 89 d8 49 8d 75 60 4c 89 ff e8 b2 76 ff ff eb 90 ff 15 12 fa 04 00 66 2e 0f 1f 84 00 00 00 00 00 48 8b 47 60 <8b> 50 04 85 d2 75 0a 48 8b 47 58 83 78 30 03 75 1b 48 8b 47 70 8b
Jun 18 15:20:33 Main-I5-Linux kernel: kdenlive[22915]: segfault at 7f8383af0040 ip 00007f8383af0040 sp 00007fff8d2639b8 error 14 in 29ca8afbff400de798d40f8ada6049af555d5ec1.qmlc[7f8383b75000+2000] likely on CPU 3 (core 3, socket 0)
Jun 18 15:20:33 Main-I5-Linux kernel: Code: Unable to access opcode bytes at 0x7f8383af0016.
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#24 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=102s
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#24 Sense Key : Not Ready [current]
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#24 Add. Sense: Medium not present - tray closed
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#24 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 16:48:27 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#25 unaligned transfer
Jun 18 16:48:27 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#26 unaligned transfer
Jun 18 16:48:27 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#27 unaligned transfer
Jun 18 16:48:27 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#28 unaligned transfer
Jun 18 16:48:27 Main-I5-Linux kernel: I/O error, dev sr0, sector 6 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 16:48:27 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#1 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#1 Sense Key : Not Ready [current]
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#1 Add. Sense: Medium not present - tray closed
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#1 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 16:48:34 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 2
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#2 unaligned transfer
Jun 18 16:48:34 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#3 unaligned transfer
Jun 18 16:48:34 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#4 unaligned transfer
Jun 18 16:48:34 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#5 unaligned transfer
Jun 18 16:48:34 Main-I5-Linux kernel: I/O error, dev sr0, sector 6 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 16:48:34 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#22 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#22 Sense Key : Not Ready [current]
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#22 Add. Sense: Medium not present - tray closed
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#22 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 16:48:50 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 2
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#23 unaligned transfer
Jun 18 16:48:50 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#24 unaligned transfer
Jun 18 16:48:50 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#25 unaligned transfer
Jun 18 16:48:50 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#26 unaligned transfer
Jun 18 16:48:50 Main-I5-Linux kernel: I/O error, dev sr0, sector 6 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 16:48:50 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 Sense Key : Not Ready [current]
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 Add. Sense: Medium not present - tray closed
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#12 unaligned transfer
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#13 unaligned transfer
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 1 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 2, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#14 unaligned transfer
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 3 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 3, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 4, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#15 unaligned transfer
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 5 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 5, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 6, async page read
Jun 18 16:49:06 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#16 unaligned transfer
Jun 18 16:49:06 Main-I5-Linux kernel: I/O error, dev sr0, sector 7 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Jun 18 16:49:06 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 7, async page read
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#4 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=35s
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#4 Sense Key : Not Ready [current]
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#4 Add. Sense: Medium not present - tray closed
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#4 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
Jun 18 16:49:10 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 2
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#5 unaligned transfer
Jun 18 16:49:10 Main-I5-Linux kernel: I/O error, dev sr0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:10 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 0, async page read
Jun 18 16:49:10 Main-I5-Linux kernel: Buffer I/O error on dev sr0, logical block 1, async page read
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#6 unaligned transfer
Jun 18 16:49:10 Main-I5-Linux kernel: I/O error, dev sr0, sector 2 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#7 unaligned transfer
Jun 18 16:49:10 Main-I5-Linux kernel: I/O error, dev sr0, sector 4 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 2
Jun 18 16:49:10 Main-I5-Linux kernel: sr 5:0:0:0: [sr0] tag#8 unaligned transfer
I also see errors related to r8168 module.
Jun 18 11:01:58 Main-I5-Linux kernel: r8168 0000:03:00.0: Direct firmware load for rtl_nic/rtl8168e-4.fw failed with error -2
Jun 18 11:01:58 Main-I5-Linux kernel: r8168 0000:03:00.0: Unable to load firmware rtl_nic/rtl8168e-4.fw (-2)
Have you tried running on the r8169 kernel module for your ethernet? In order to do that you would need to uninstall the r8168 package and reboot. Then check if ethernet is working
inxi -Na
Also notice you are using lightdm on Kde. Just wondering why?