HTTP 503 Unavailable

When I use “” the SmartLock opens, but for 14 seconds I will get the 503 error.
I send this command from a python script. Before starting the command I’m logging the start and I’m also logging after the command and there will always be 14 seconds between.

I have two bridges - each with one SmartLock, both SmartLocks with 1.9.3.
This behaviour only occurs on the older bridge with firmware 1.15.1.
On the other bridge with 2.5.2 there is no delay and also no 503.
Both bridges don’t have issues in my router logs relating wifi/dhcp or firewall.

Is there a solution for my problem with the bridge on firmware 1.15.1?