Tailscale just stopped working since a few days

So far everything went super smooth. I was using tailscale on Synology (DSM7) NAS to access securely via my iPhone. But since a few days it stopped working. I did not change anything in my network / setup.

I already redownloaded and reinstalled tailscale the iPhone but it does not work. The devices on the tailscale website show “connected”. But access via iPhone on mobile does not work anymore …

… ok I uninstalled and reinstalled the Package on Synology. Now it works. Weird … there was no update / change or anything similar … ?!?