Bit confused. You say the issue is not on other devices. Does that mean they continue to work okay? Does issue occur if the PC is connected via WIFI? Have you tried a different cable between the...

No idea. Sounds like you are working to isolate the issue. I suspect the PC more that the router. I would try the following: Power all off and let it cool down, remove the PC from the router, power...

I see you are on the newer Green User Interface as I am on the old Blue User Interface. The Green Interface lost some functionality on my C8 so I went back to the Blue one. The Blue interface on my...

Bypass the router and connect your PC direct to the Modem and see if you have upload speeds. If you have good upload speeds, the issue may be in your router. If no upload speed, then check your modem...

Depending on version level, the user interface changed a while back from blue to green and the options are different. The few times I needed to reset a router, the above worked. Did your router allow...

I also buy hardware with the future in mind so I do not have to keep replacing it over time and it is a better value IMHO. Any of those would work, but if it were me, I would lean toward the fastest...