Alright so I did some investigation and found that my docker daemon wasn't exposing port 2375 or 2376 locally anymore.
To fix this I navigated to the config folder on the Unraid Server:
/boot/config/
Nano into 'docker.cfg' and added this section:
DOCKER_OPTS="-H unix:///var/run/docker.sock -H tcp://0.0.0.0:2376"
Saved the config and restarted the docker service with:
/etc/rc.d/rc.docker restart
All is working well and my uptime kuma service on my desktop pc can see the docker containers on my unraid server again.