I’m fairly sure this isn’t a Tailscale issue per se, but it is reproducible in certain circumstances and maybe you could work around it. The issue is:
- Tailscale running on iOS (all updates)
- Cellular connection, no WiFi in range
- Everything is fine, can access public and private networks as you would expect
- iPhone travels through an area of terrible cellular coverage (won’t be able to receive calls/sms/use data network)
- When cellular coverage is restored the iOS data networking is half broken
The symptoms are that basically any higher level network apps will fail, whether they are accessing the Tailscale network or the public one. So a Twitter client won’t load, web pages won’t load, Calendars won’t refresh, ssh to private Tailscale IPs fail). The Tailscale client shows as connected, and the iOS VPN status in settings does too.
Even though most networking fails, functions like ping to 126.96.36.199 work fine, making the network seem functional to some degree. The fix is to turn Tailscale off then back on and things are back to normal.
The reason I don’t think this is unique to Tailscale is that I’ve seen the same behavior using the Guardian iOS firewall (https://guardianapp.com). This is implemented as a VPN as well, and it exhibits the exact same behavior (I’m not using them at the same time, but they do the same thing independently).
This seems like it is an issue with iOS, but if you can detect it the fix seems to be something that Tailscale could implement. The problem shouldn’t be very widespread…I have never seen it in an urban setting, but I regularly travel through some rural areas where it happens each time.