Unable to log into client

Could be a ton of things, let us start somewhere:

Flush DNS

https://support.pearson.com/getsupport/s/article/Reset-an-Internet-Connection-Flush-DNS

Navigate to the desktop. (From Home, tap or click the Desktop tile).
Right-click the Start button (the Windows logo in the lower-left).
Choose Command Prompt (Admin).
When asked whether to allow Command Prompt to make changes to your computer, select Yes.

Note: If you are asked for an administrative login, you will need to contact your system administrator.
Type "ipconfig /flushdns" and press Enter.
Type "ipconfig /registerdns" and press Enter.
Type "ipconfig /release" and press Enter.
Type "ipconfig /renew" and press Enter.
Type "netsh winsock reset" and press Enter.
Restart the computer.

done. Did not work.
Thank you...for this, at least

What kind of router do you have?

For testing purposes put your PC into DMZ in your router UI and test again.

done, still no cigar 😞

i find it hard to believe this kind of thing happens rarely...with all the shi.t cheap routers out there...

Try disable ipv6 maybe. Disable any network adapters except you current adapter.

this sucks...

I have the same problem, im also on win10...

Btw i have a very similar type of router like you, since were both croatian, you on optima ?

im optima to win 10 same problem