oh you need to add an env parameter to fix the upstream issue. it's specific to umbrel. let me see if i can find it. i don't have my umbrel any longer or i'd just look to see what i did.
I originally tried running cloudflared by itself but there's issues accessing the dashboard because I guess Umbrel doesn't support SSL by default so you're limited in what you can do on the tunnelled connection.
I'd prefer to not be using Umbrel at all but its for a less technical user that's never going to be updating docker containers on their own so keeping the container management intact will be a necessity. I look forward to nostr:npub126ntw5mnermmj0znhjhgdk8lh2af72sm8qfzq48umdlnhaj9kuns3le9ll's networking stack being released so I can just tell them to download StartOS and be done with it all.
Discussion
found it!
add this file:
~/umbrel/app-data/btcpay-server/.env.app_proxy
add this line to file:
PROXY_TRUST_UPSTREAM=true
bounce btcpayserver:
~/umbrel/scripts/app restart btcpay-server