upgraded to 18.04, now thunderbird will not connect to server

Right after upgrade ubuntu to 18.04 (from 16.?), thunderbird will not connect to the server. Have tried multiple new settings. Posting same question on mozilla community. No problem with upgrade or internet connection afterwards. Using thunderbird 60.8.0. Original POP settings to a comcast server. Incoming - POP mail server, server name mail.comcast.net, port 995. Outgoing - smtp.comcast.net, port 465.