|Why aren't you contacting whoever set these up?|
Have you talked to Grande?
From what you write, it appears you don't have all the information on how this communication between the two routers was set up.
You mention ip addresses but those are for the lans on each side. You should be more concerned about the wan ips, how the routers communicated [VPN?] and what changed [power going out doesn't reset a router(s) which when powered up should come up as before].