Tor onion addresses do not use regular IP/domain assignation. That makes easier for node operators to run their nodes with home connections (dynamic IPs) and also no need to open ports on the router. Each app from Umbrel node will have its own specific onion address (that regularly will use a specific port).
Read more here
Tor-Only BTC/LN nodes – by Jameson Lopp
And here you have a complete list of resources about nodes and LN