One computer in my home home network can't connect to zoom

There are plenty of devices in my home network - tablets, laptops, smartphones - all of them are able to connect to zoom without a problem. As expected.

But I have one device, and old iMac, that can't connect to zoom.us. The issue is with the zoom app, and with every browser I'm trying. The browser shows a timeout error.
I've tried to look of there's a firewall, a faulty hosts file on the computer, or even an issue with the router, but couldn't find anything.

I've tried uninstalling the zoom app, using the uninstall procedure, but that didn't help either.

I can't find any similar issues online.

I'm kinda lost for solutions here.

Can someone help me please?