Yo, I feel your pain. Setting up Gmail proxy over Thunderbird can be a nightmare. One thing that worked for me was disabling the "OAuth2" authentication in Thunderbird and switching to "Normal password." For some reason, OAuth2 kept failing for me.
Also, double-check your proxy IP and port. Sometimes the proxy provider gives you a list of ports, and you might be using the wrong one.
Hope this helps!
Also, double-check your proxy IP and port. Sometimes the proxy provider gives you a list of ports, and you might be using the wrong one.
Hope this helps!