The connection speed has become 10 Mbps instead of 100 Mbps and the browser does not work?

Question

Computer networks

The connection speed has become 10 Mbps instead of 100 Mbps and the browser does not work?

The site did not open in the Mozilla browser, it says: TLS handshake and it hung on it. Opera has a DNS error.
FTP worked.

Disconnected the cable and reconnected it. The connection speed was 100 Mbps and the sites began to open.

The Internet is connected through a router to a computer via a cable. Before that, the cable from the router was disconnected. I plugged in the cable, started the computer and that's it.

At this time, everything worked from the mobile.

Answer 1

Rebooted the port and everything started up. And so maybe dust appeared on the connector, maybe it oxidized a little, maybe the core began to break, who knows? A universal recipe is to change the connector and plug in a second wire.
Out of 5 ports on my Mikrotik, only two remained alive in 7 years.

Answer 2

There is a possibility that you need to re-compress the cable (RJ45 connectors). It was a couple of times at the facilities. There is just no contact in the connector and that's it.