Welcome to the forums!
I guess we need to start at the start…
From groov Manage on one of the EPICs (just start with one, get it going, then move on to the other) go to the network tools. System → Network → Diagnostics (at the very bottom).
Start with ping and try and ping google.com, then try and ping your broker (they might have ping turned off - hence testing Google to start with).
If you cant, then there is your MQTT problem, your EPIC does not have its network configuration setup correctly. Either the DNS (domain name server) or gateway is messed up.
If you can ping, then we turn to Node-RED.
Of course you have double checked your broker host name and its user/pass.
I don’t know your broker all that well, but some require legacy mode:
Check the box (its clear by default) and deploy and see how you go.