It may be worth a try. Possibly also trying to setup the connection again in it. Do the logs give anything away from that time? The timing just seems a little suspicious that it is something automated somewhere, like a reboot following some other changes or something like that.
Also worth trying another router (which I think you've said you're already trying to do), to rule out (or in) an issue with your account.
Just to go back to one of your original questions, I'm using a third party router without any issue. There's quite a number of people doing so too, so if it was wide spread issue with third party routers on Plusnet, I'm sure we'd have heard from a lot more people. There are others on OpenWRT as well, but likely a much smaller number.
My guess (and it is only a guess!) is that its either something with your router or your account. Hopefully you can work out which and fix it pretty quickly (or Plusnet can if it's account related).
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
