Maybe something about the network. My first thought was perhaps the ISP is blocking certain kinds of traffic, but since you tested a VPN and had the same issue I’m not sure.
I just tested adding the repo from the EOS live environment and it worked fine.
[liveuser@eos-2024.06.25 ~]$ sudo pacman-key --recv-key 3056513887B78AEB --keyserver keyserver.ubuntu.com
gpg: key 3056513887B78AEB: public key "Pedro Henrique Lara Campos <root@pedrohlc.com>" imported
gpg: Note: third-party key signatures using the SHA1 algorithm are rejected
gpg: (use option "--allow-weak-key-signatures" to override)
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 12 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 12 signed: 93 trust: 0-, 0q, 0n, 12m, 0f, 0u
gpg: depth: 2 valid: 70 signed: 20 trust: 70-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2025-01-25
gpg: Total number processed: 1
gpg: imported: 1
[liveuser@eos-2024.06.25 ~]$ sudo pacman-key --lsign-key 3056513887B78AEB
-> Locally signed 1 key.
==> Updating trust database...
gpg: Note: third-party key signatures using the SHA1 algorithm are rejected
gpg: (use option "--allow-weak-key-signatures" to override)
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 13 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 13 signed: 93 trust: 1-, 0q, 0n, 12m, 0f, 0u
gpg: depth: 2 valid: 70 signed: 20 trust: 70-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2025-01-25
[liveuser@eos-2024.06.25 ~]$ pacman -U 'https://cdn-mirror.chaotic.cx/chaotic-aur/chaotic-keyring.pkg.tar.zst'
error: you cannot perform this operation unless you are root.
[liveuser@eos-2024.06.25 ~]$ sudo pacman -U 'https://cdn-mirror.chaotic.cx/chaotic-aur/chaotic-keyring.pkg.tar.zst'
warning: no /var/cache/pacman/pkg/ cache exists, creating...
:: Retrieving packages...
chaotic-keyring 28.7 KiB 48.6 KiB/s 00:01 [------------------------------------] 100%
loading packages...
resolving dependencies...
looking for conflicting packages...
Package (1) New Version Net Change
chaotic-keyring 20230616-1 0.03 MiB
Total Installed Size: 0.03 MiB
:: Proceed with installation? [Y/n]
(1/1) checking keys in keyring [------------------------------------] 100%
(1/1) checking package integrity [------------------------------------] 100%
(1/1) loading package files [------------------------------------] 100%
(1/1) checking for file conflicts [------------------------------------] 100%
:: Processing package changes...
(1/1) installing chaotic-keyring [------------------------------------] 100%
==> Appending keys from chaotic.gpg...
==> Locally signing trusted keys in keyring...
-> Locally signed 5 keys.
==> Importing owner trust values...
gpg: setting ownertrust to 4
gpg: inserting ownertrust of 4
gpg: setting ownertrust to 4
gpg: inserting ownertrust of 4
gpg: setting ownertrust to 4
gpg: inserting ownertrust of 4
==> Disabling revoked keys in keyring...
-> Disabled 3 keys.
==> Updating trust database...
gpg: Note: third-party key signatures using the SHA1 algorithm are rejected
gpg: (use option "--allow-weak-key-signatures" to override)
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 16 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 16 signed: 93 trust: 0-, 0q, 0n, 16m, 0f, 0u
gpg: depth: 2 valid: 70 signed: 20 trust: 70-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2025-01-25
==> Updating trust database...
gpg: Note: third-party key signatures using the SHA1 algorithm are rejected
gpg: (use option "--allow-weak-key-signatures" to override)
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 16 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 16 signed: 93 trust: 0-, 0q, 0n, 16m, 0f, 0u
gpg: depth: 2 valid: 70 signed: 20 trust: 70-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2025-01-25
Optional dependencies for chaotic-keyring
pkgstats: install to submit package usage statistics
:: Running post-transaction hooks...
(1/1) Arming ConditionNeedsUpdate...
[liveuser@eos-2024.06.25 ~]$ sudo pacman -U 'https://cdn-mirror.chaotic.cx/chaotic-aur/chaotic-mirrorlist.pkg.tar.zst'
:: Retrieving packages...
chaotic-mirrorlist 3.3 KiB 8.76 KiB/s 00:00 [------------------------------------] 100%
loading packages...
resolving dependencies...
looking for conflicting packages...
Package (1) New Version Net Change
chaotic-mirrorlist 20240724-1 0.00 MiB
Total Installed Size: 0.00 MiB
:: Proceed with installation? [Y/n]
(1/1) checking keys in keyring [------------------------------------] 100%
(1/1) checking package integrity [------------------------------------] 100%
(1/1) loading package files [------------------------------------] 100%
(1/1) checking for file conflicts [------------------------------------] 100%
:: Processing package changes...
(1/1) installing chaotic-mirrorlist [------------------------------------] 100%
[liveuser@eos-2024.06.25 ~]$