Pihole does not process client requests anymore

Situation

I have set up pihole on my synology nas using portainer. It worked fine for several weeks. Two days ago, I set up home assistant in a VM on the synology nas. In order to do so, I had to activate the "open vSwitch" support (click the check box in the synology settings).

Current Behaviour:

To my knowledge, since activating openvswitch, pihole does see my other devices as clients in the network, however none of the DNS queries seem to be processed by it, unless those coming from the nas itself. DNS queries on all other devices are painfully slow now (up to 4seconds).
I have tried to stop and start the pihole stack as well as reinstalling it several times. Did not work. Same problem.

Debug Token:

Here is the debug token: https://tricorder.pi-hole.net/m5DIuK2B/