I've tried adding the port (50002) to the Avast exclustion list that is listed next to the servers in the "Network" settings but it doesn't seem to help. When I completely disable the Web Shield Electrum connects just fine. Are there other ports I should be adding to the exclusion list or is it something else altogether?
I think you will also need to allow destination ports 80 and 110.
Thanks, to you both for the suggestions.