I am unable to upload files larger than a few MBs anymore after “upgrades” done in my area.

I’ve called twice about the issue, I’ve changed nothing on my end - after “upgrades” done in my area, this one part of my service no longer works. Everything else is fine - can connect, stream videos, play games, use apps, download, etc.  But no matter what device or browser or app or website, every upload more than a few MBs is cut off partway through and gives “Network error” as a reason.

This post is my last chance to get it resolved as the agent on the phone just told me to contact my modem manufacturer for help with the service they somehow broke and can’t fix.  Been through the whole process with online and phone support, escalating to level 2, with no resolution.

If this doesn’t do it, AT&T just put in fiber in my neighborhood and I can get it cheaper than what I am paying you guys so I am about to switch after being a customer since 2018 with no previous issues.

It’s not on my end, I didn’t change anything. Other people have posted here about having this same issue after “upgrades” in their area.  Tell me what to do to fix it or else I need to just get a different service that works.