Comment 9 for bug 1834501

This breaks me quite often as well.
Even in cases where I "COULD" set up a httpproxy.
Let me add a showcase:
1. Bionic was fine, apt and software installs worked fine
   E.g. the network was setup to allow the archive.ubuntu.com in the FW
   But not for anything else (e.g. snapstore)
2. do-release-upgrade will fail half way through with all the pain of broken installs and such. Really painful to recover and a bad experience

I was wondering if Bionic's do-release-upgrade should check and only get started if it can verify that snapd can reach the store (or enterprise proxy or any else).
This won't solve all of the original bug (air-gapped still have issues) but it would avoid a lot of people that are not air-gapped but have special handling for archive.ubuntu.com in place yet nothing for the snapstore to fight this in a broken upgrade. They could adapt the setup as needed upfront and then have a smooth experience on the upgrade.