503 Service Unavailable - no available server

etienne31 — Wed, 08 Apr 2026 12:10:14 GMT

Since today (April 8th), I started to experience problems with the API.

10:30 UTC - Read timed out (Error 500 after 30s)

10:35 UTC - 401 Unauthorized

10:40 UTC - Read timed out (Error 500 after 30s)

10:45 UTC - OK

10:50 UTC - Read timed out (Error 500 after 30s)

10:55 UTC - 503 - no available server

11:00 UTC - 502 Bad Gateway

11:05 UTC - 503 - no available server -> until 11:45 UTC - always 503
Then 11:50 / 55/ also 503

Now 12:00 UTC - Read timed out (Error 500 after 30s)

It looks like problems on Viessmann server side, right ? Or should I do something ? I already tried to reboot everything, but no success.
Thanks!

Betreff: 503 Service Unavailable - no available server

etienne31 — Wed, 08 Apr 2026 12:09:02 GMT

Also, I would like to point out the frequency of API outage which is starting to become really problematic as the consequence for us could be :
- no heating
- no hot water
- no cooling
- electricity consumption during surge fares
All of these are really annoying when they happen too frequently.

That's why I'd really like to have a solution in order to drive the system locally without cloud servers.
Is there any protocol to directly talk to the vitoconnect in the same local network ?

Thanks

Thema "503 Service Unavailable - no available server" in The Viessmann API

503 Service Unavailable - no available server

Betreff: 503 Service Unavailable - no available server