BIND (forwarder+cached) - serve cached if forwarder fails

Solution 1:

Using expired data is a really strong "must not" in the standards, so it would surprise me greatly if it's possible to get BIND to do that at all. You may want to look into alternative resolvers more closely aimed at personal use, or (since it sounds like your ISP intermittently blocks traffic to port 53) try getting a VPN tunnel and have your BIND use that.