Cannot connect Eudora to Yahoo.mail

I have been using Eudora for over 20 years to access my Yahoo Mail account via POP without too many problems. Three weeks ago Eudora stopped being able to do incoming mail from Yahoo, although it could send emails OK. Error message : " Cannot connect to pop.mail.yahoo.com Cause: connection timed out"
I use the same settings to access Yahoo Mail via a browser or with Thunderbird app. I do not want to lose all my 20 years data on Eudora. Imap is not really feasible as I have some 15GB of emails, and that will not fit on the Yahoo server. Tried it , but same error message.
I went through the whole rigamarole with Yahoo Customer Service, new App special passwords, checking SSL settings etc, but no improvement. Yahoo claim they have not changed anything , and to talk with Eudora. Eudora was sold in 2006 and the new owners did not develop or support Eudora, so Eudora did not change 3 weeks ago.
I suspect it is the security certificates that Yahoo have changed, and which old Eudora cannot handle.
I have tried stunnel, without any success.
Can anyone please suggest a way forward?