Hi Nina Au 

Are you are connected to a VPN, please check if the error still occurs after disconnecting from it.
I also assume others can connect error free?

While I appreciate you mention reinstalling, I would manually ensure the following are refreshe

• For Studio 2021: C:\Users\[Username]\AppData\Roaming\SDL\SDL Trados Studio\Studio16
• For Studio 2022: C:\Users\[Username]\AppData\Roaming\Trados\Trados Studio\Studio17

Rename the file Settings.xml, for example to Settings.xml_OLD.
This is a rare issue caused by invalid server connection details within the Trados Studio Settings.xml file.

I would also check and remove things listed here depending on verion

• For Studio 2021: C:\[username]\lsimplicio\AppData\Roaming\SDL\Platform\Identity\SDLTradosStudio.exe
• For Studio 2022: C:\[username]\lsimplicio\AppData\Roaming\Trados\Platform\Identity\SDLTradosStudio.exe\SdlIdentityCredentials

Perhaps Alex Jude has other suggestions so please do update post following my advice 

Lyda