Suddenly getting connectionn refused when thunderbird tries downloading email

I read and send my cox email using thunderbird on my Windows laptop. It was working fine yesterday,  but this morning send works but get mail either gets an error message connection refused or it acts like it works (no error msg) but  it does not retrieve email.  (I can see new email is there if I log into my account using a browser.

Does anyone know what the problem is?  I tried chatting with cox tech support but they were clueless.