I have the same issue. I've bought a whole new cable to try to see if maybe that was the issue. The cable was not the issue. Although my internet is only 1g when I first set up the motherboard I plugged the cable into the 5gb port without realizing until these issues started occurring. I called Asus support and got on the phone with some Indian guy that I could barely understand. It was frustrating because I dug up so much information that I was trying to tell him and all it came down to was that I had to wait another 48 hours for a call of "higher technicians." That never happened... So I took the issue into my own hands and dug around more finding drivers and other people having the same problems. I reverted back to one of Aquantia's older drivers for the port I think It was 2.1.14.0. This fixed the upload speed issue but for me at least I began to see connection disruptions in other games. It was very annoying to me that one port could have so many issues. I even contacted Aquantia's support email to see if it may be a known issue and maybe they have a fix. Never got a response. I came to the conclusion that It had to be driver issues on Aquantia's end. You are the first person I've seen with the same model having the same issues that are recent. The rest of the posts I've seen were dated back to 2019. It's sort of relieving to see someone else so I don't feel like I'm the only one with the problem. I didn't want to go through the trouble of RMA the board so I just stuck with the Intel port. If you end up finding out what the cause is or what you end up doing please let me know. Goodluck!