Nginx Proxy manager not able to forward to ip-Address (99: Address not available)

Hi guys,

I am really having some trouble to get the nginx proxy manager to work properly.
Any help is appreaciated.

My Home-Assistant (2023.4.6)runs on a rpi4 and so far no problems. Now I want to access it from the outside world. Since I am a customer of Deutsche Glasfaser I do not get a unique IPv4-address and have to use IPv6.

What I did so far:
I got the IPv6 address of home assistant from my fritzbox. If I use http and the ip-address I can access Home Assistant. Then I wanted to add ssl and a domain name. I bought a domain at strato and added the ip-address as AAAA-record. This works also.

I unlocked home assistant in the fritzbox

Then I added the NPM addon and was able to set up a proxy host including a ssl certificate from let’s encrypt.

Now my problem:
In the logs of npm I see that request. NPM trys to forward it to the IP-address of home assistant but thows the error:

> 2023/06/18 16:56:46 [crit] 556#556: *177 connect() to [XX:XX:XX:XX:fbc0:2737]:8123 failed (99: Address not available) while connecting to upstream, client: 172.30.32.1, server: XXX.de, request: "GET / HTTP/2.0", upstream: "http://[XX:XX:XX:XX:fbc0:2737]:8123/", host: "XXX.de

Also good to know: If I use domain from within my network, it works.

I am not sure to where to look anymore. Especially I don’t find any clues on the 99-Error.

Thanks for your help in advance

Markus