MS Teams Company Portal & Time

When first setting up a desk phone for Teams running Android 7.x it will always “hang” at Company Portal unless the time/date is set correctly. At which point I can log in normally.

Can anyone explain why that happens? It defaults to automatic time/date set which fails to change from 1970 unless manually entered and *then* automatic time/date is turned on, which then works.

This is reproducible on different makes and models of hardware so doesn’t seem to be device-specific.