Pixel 2 XL
ZoiPer 2.8.39 (but it's the same with any version)
"Push service" subscribed, enabled
Enabled networks: wifi, 4G
Problem: when I leave home (wifi) and the phone switches to 4G, in 30% of cases Zoiper FAILS to re-connect, MISERABLY. It tries for hours, killing the battery. Sometimes returning to wifi helps, sometimes it does not.
Manual SIP-account enable/disable inside ZoiPer does not help. Manual exit/restart of ZoiPer does not help.
The only workaround I found - go to system-settings->ZoiPer->app-info, then FORCE STOP, and restart ZoiPer. This way it reconnects immediately in 100% of cases.