Comment 3 for bug 1987236

https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L213

This seems to be the relvant code. As I don't know the first thing about s390x networking I'm reluctant to make changes.

Are you saying that chzdev_persist_active_online() should be an optional step, where the install attempts to proceed even if it fails?

I can prepare a snap with that change if you help test.