https://www.thinkbroadband.com/broadband/monitoring/...
It seems since I rebooted my router BQM is no longer working on my Plusnet line, but is fine on the Zen line to the same router.
I checked the firewall rules multiple times and they are the same, can ping my Plusnet line from my VPS and even tried a few websites that ping from around the world, all can ping it fine.
I even tried changing BQM to the domain name thinking it might detect a change and somehow kick it back into action, but no joy.