you can't really troubleshoot things that far with little info, for all i know your miners might hang and all they need is a physical off and on action, if you can get someone to do that, and you still can't access them , then you go to phase 2 of troubleshooting which is security.
I do have a few miners that i can't physically reach ( takes time to get there), and i don't go through all the mess of port forwarding and exposing anything out the lan, i bought a very cheap second-hand pc for less than 150$ and i use teamviewer to access my miners, i also have someone there who can reach the miners in a few mins if they need a reset or any on-site actions.
if you can't have it that way then you should consider smart MCB for both miners and router , i don't know about others, but to me , a physical restart/reboot is always important, never had a miner in a passive state for over a year, they always need something to be done onsite.