I think I may have figured out how to work around the issues I have been having with Comcast. Sometime about 2 weeks ago Comcast IPV6 stopped working, but their network was still connecting as if it was. If I turn off IPV6 on my end, my backup starts working again. The python library that duplicity uses to access Google storage no longer tries to access it via IPV6. Rather it uses IPV4 and it works.
Huzzah!
Next, set aside time to deal with Comcast support so IPV6 can work.
Huzzah!
Next, set aside time to deal with Comcast support so IPV6 can work.