Comment 8 for bug 1850272

From your log:
Okt 17 15:28:57 nc158-muc nginx[1296]: nginx: [emerg] bind() to 172.18.8.1:80 failed (99: Cannot assign requested address)
Okt 17 15:28:57 nc158-muc nginx[1296]: nginx: configuration file /etc/nginx/nginx.conf test failed
Okt 17 15:28:57 nc158-muc systemd[1]: nginx.service: Control process exited, code=exited status=1
Okt 17 15:28:57 nc158-muc systemd[1]: nginx.service: Failed with result 'exit-code'.

Maybe the server just starts to early.
Can you replace for a test
After=network.target
with
After=network-online.target
IIRC?

There is a whole category of such issues and it eventually comes down to user-config, but it might be worth to check if that dependency would make it work for you.
You can even wait for the device itself.