I don't use any antivirus - only windows defender. It's worth mentioning, that in the past I've had dns related problems in other games, that require launchers. In some cases I asked for help technical support of those games, and technicians would spent whole days with me (on discord, skype or whatever) trying to resolve the dns errors, and in every case, they just ended giving up saying that they have no idea what's wrong with my pc and that it's the weirdest case they had ever encountered. So it's not only swtor. What can be wrong? Are there any, idk, connection/dns tests I could run?
try https://www.windowscentral.com/how-change-your-pcs-dns-settings-windows-10
maybe start with google 8.8.8.8 and 8.8.4.4
just to add the only thing that can override a dns server is a localhost entry https://support.microsoft.com/en-us/topic/how-to-reset-the-hosts-file-back-to-the-default-c2a43f9d-e176-c6f3-e4ef-3500277a6dae
also if you havent reset the winsock on that system https://help.iinet.net.au/resetting-network-adapter-winsock-reset
I've already tried changing dns (tried multiple ones, not only google) and overriding the host file.
I haven't done the winsock reset, so I did it just now (with a pc restart just to be sure) and still no luck.
try type the below similar to the winsock
netsh int ip reset
edit - you can check the integrity of that windows install too by
sfc /scannow
