Basic question. Have you downloaded latest drivers for your motherboard lan from the manufacturers website and installed them?
#why(fi) my wifi so slow?
twilit sun
limpid tusk
^^^^^^^ the above might help. Otherwise, how long is the cat 6a run? Can you give us an overview of how your PC is connected to the ISP connection? Drawing or text based is fine. What modem, router and switches are you using?
twilit sun
Is it an isolated issue that only affects your computer or do you also get low speed on WiFi?
Do you have either PCI ethernet card, external USB ethernet dongle or a different computer entirely that you could try with the given cable? I have seen motherboard ethernet port inexplicably die before.
Then it's not an issue of your computer. It's a longshot but I had a shitty router some 20 years ago which did similar thing. The only thing that would fix it was disconnecting it from power for a few minutes and then starting it up again. Try it
Generally things like that happen in internet service provider branded network equipment because they buy garbage stuff, give it own logo and ship it.
limpid tusk
Exactly. If your network perf goes down, usually buying your own router and wifi ap is a good idea. And I would always recommend building a router yourself (just a small server running OPNSense or pfSense)