1Gb limited to 100Mb capacity
1Gb limited to 100Mb capacity
At this stage, it seems there might be an issue with the adapter that testing tools can't identify easily—though it’s uncommon. Alternatively, something could have failed within Windows itself. My next move would be to try a dual boot to confirm or rule out software problems.
Created a bootable USB using Kubuntu 19.10 and experienced significant performance issues. Speed tests exceeded 900Mbps during the run.
To try and restore stability without fully reinstalling Windows, I used a TCP optimizer to adjust several system settings. It appears this has resolved the issue temporarily.