As @cygan said by default Umbrel is running on TOR and you cannot disable that for now.
You *do not* need to use port forwarding it all just goes through the TOR network for connections to the outside world.
However, you should have more then 1 connection.
-Dave
Are you sure Umbrel with Tor will have many inbound connections?
Not 100% sure since I have tinkered with mine a lot, all I can say is mine DID before I took it offline last month.
Take a look here:
https://community.getumbrel.com/t/is-there-a-way-to-increase-the-number-of-peers/5150 You might want to post a question there too and see. The community is active and willing to help.
Side note, before opening ports make sure you understand the security implications of letting ANY inbound traffic into your network.
-Dave
I think Tor could receiving more than 10 inbound connections.