Strange problem with the Ethernet port, how to fix it?

Question

network hardware

Within a few days, I noticed network breaks in games, that is, you play for 10-15 minutes and by this time the network will definitely break and then it will turn itself back on after a while (you could speed it up by constantly turning the adapter on / off. And In ordinary Internet tasks, everything works fine, but as soon as we put a more or less serious load on the network, breaks occurred almost immediately.
Initially, I sinned against the provider, I already wanted to call the masters, but I noticed such a trick that when the PC lost the network, the WiFi on the phone continued to work fine (the PC is connected via LAN from the router, when the main LAN is directly connected, the same story with breaks). For several days I was looking for what the problem was, but I did not find an answer, to delay the breaks (about 40-50 minutes of a quiet game, and then a break), setting up the network adapter through the device manager helped, turned off power saving and auto-speed reduction.
And the main feature is that the Internet is working, but the connection indicators on the LAN port of the motherboard are not. I tried it on the laptop, everything is on fire there (that is, the problem is also not in the cable). I suspect that with recent thunderstorms, the LAN cable has slightly spoiled the port (if this is of course possible).
In general, I don’t know what to think next and how to solve this problem, I’m waiting for your answers and possible solutions)

Answer 1

1) Replace or recompress the cable, change the port on the switch (this is the simplest, fastest and cheapest diagnostic that eliminates stupid problems)
But most likely
2) Install another network card, since your isolation transformer most likely burned out
In this case , in the presence of crazy handles, it is possible
3) Replace the transformer. Most likely, it is combined with the connector.

Answer 2

about "change the port" - they meant on the side of the router, try plugging the cable into another port
, but most likely the problem is in the network card, buy another one

Answer 3

If anything, then the problem was solved by a banal purchase of a network adapter)