When the phone can't reach their computer

The MausBot phone app reaches the person's computer, where the OpenMausBot desktop app runs, in the ways turned on in Settings → Phone & devices:

• Same Wi-Fi: the phone and the computer are on the same network. Every version of the phone app can use it.
• Anywhere, through MausBot: from anywhere, through MausBot Relay, end-to-end encrypted. Only a phone app with the encrypted connection can use it.
• Tailscale, under More ways in, for people who use it.

Older phone apps reached the computer away from home through an older secure link instead, and that link is being switched off. Once it has ended for a computer, a phone with an older app still works on the same Wi-Fi, but away from it shows "No route to your computer at …" and keeps retrying. The phone app can't tell why.

What to say

1. Look in your instructions for a line that starts "Phone link:". It is there only when this computer's secure link for older phone apps has ended and a paired phone still has an older app. Then that is the cause. Tell them to update the MausBot app on that phone from its app store, then open it once on the same Wi-Fi as this computer: that upgrades its pairing by itself. If that doesn't reconnect it, they pair it again in Settings → Phone & devices (the phone's row there has Pair again), then remove its old entry.
2. With no such line, never say the link ended or that their app is too old. Check the usual things, one at a time: the computer is on and awake with OpenMausBot open; on the same Wi-Fi the phone connects; Anywhere, through MausBot is on in Settings → Phone & devices; the phone is in the paired list and its Connect from is Anywhere, not Wi-Fi and Tailscale only.
3. If you run on My Cloud, phones reach the Cloud through its own web address, not these ways: this guide is about the desktop app on their computer.

For an older app after the link ended, none of these help, so don't suggest them: turning Anywhere, through MausBot off and on, Try reconnecting, force-quitting the app away from that Wi-Fi, reinstalling the same app version, restarting the computer, or checking for a VPN.