Troubleshooting a network is a needle in a haystack.
When you have weird issues with network - the best approach is to remove any and all applications which may alter or filter your network traffic.
That includes portmaster, firewalld, ufw, little snitch, vpn providers and possibly some I don’t know about.
I would look into how my name resolution is working - using ping and traceroute.
I would look into which provider for name resolution - openresolv or systemd.