Jackett not reachable after a while

Hi, I recently switched to the Jackett docker version and have a strange problem.
After a system reboot, Jackett runs fine, after a few hours(?) the web-interface is not responding anymore. It looks like the docker container is running ok. In the docker logs, I just see that sometimes the update check fails:
System.Net.Http.HttpRequestException: Resource temporarily unavailable (api.github.com:443)

Even after I restart the container, the issue persists. I tried restarting with
docker-compose restart & docker-compose up -d --build --force-recreate

The only way to fix this, is a machine reboot.

My OS is: Ubuntu 20.04.1 LTS
My Docker: 20.10.1, build 831ebea
Docker Compose yml:

version: ā€œ2.1ā€
image: ghcr.io/linuxserver/jackett
container_name: jackett
- PUID=125
- PGID=131
- TZ=Europe/Brussels
- AUTO_UPDATE=true #optional
- /home/docker/.config:/config
- /home/docker/Downloads:/downloads
- 9117:9117
restart: unless-stopped

Any ideas what is happening here or how to debug this? Iā€™m pretty new to docker, so not experienced how to get to the root of this problem.

Thanks for any help

Looks like I found it. Was nothing within the container, but some problem with Docker Networks and ExpressVPN. Unfortunately looks like a dead end.