Terrible new development.
While disabling fastboot I thought to ““test”” my connection on windows by downloading the same file i tried to on Endeavour, and got the same result.
In addition I’ve realized that my phone was automatically connecting to the old router from the previous ISP (Xfinity) instead of the new AT&T one, I feel stupid for not noticing this sooner but at least I didn’t spiral because of Windows for a second time in my life.
Assuming this meant that every single one of my previous tests using the phone were invalid, though only the USB Tether one was, I tested my connection from the phone AGAIN.
Though this is worse than the first results from 3 days ago, it still doesn’t look terrible. This time though I also started a file download on it for the first time in this thread, just to check if I had missed something back then.
Turns out, I did.
For comparison, here are both of the same things done exclusively using Mobile Data (file download is significantly faster, though everything else is predictably worse).
I think this rules out any inkling of a thought this could have anything to do with my setup.
That may also mean I didn’t have to update my BIOS, but that’s ok because as you’ve stated it’s still best to keep that up to date anyways.
I’ll contact AT&T about the issue soon, since it seems like their router (or worse, the local infrastructure) may have been the cause all along.
I’ll reply with any updates on the matter as they come along, I’m very sorry if I’ve wasted your time.