I've been using Traefik for some years to provide security for my docker containers, and it's worked fine. Anyway, I'm just now updating my docker setup - which is pretty ancient in docker terms - and I've updated to Traefik version 2.5, which I've pulled with docker-compose. (I have a traefik.toml file which I must have constructed years ago and not looked at since: I'm a set-and-forget sort of guy.)
Anyway, the container simply fails to start. When I enter docker container ls for example, I find, with the Traefik container its status is always something like Restarting (1) 8 seconds ago. (With differing number of seconds.) I have set restart: always in my container definition in my docker-compose file, but I don't know why this is happening. All my other containers start; only Traefik doesn't.
What would be preventing Traefik from starting, or more to the point - how do I find out what the problem is? Thank you!