Unable to access NextCloud on local lan

Could be an issue if you have no port opened in your router:

  1. you connect e.g. 192.168.1.56
  2. NC will redirect you to ddns nost
  3. ddns host is bounded to your externals ip, e.g. 100.100.100.100
  4. your browser will try to access https://ddns host/ on 100.100.100.100
  5. If 443 port closed - you failed to connect.

That is correct, now you will be redirected to https://ddns host/ on 192.168.1.56 instead 100.100.100.100. You can also use your hosts file locally without any modifications on router for such kind of things.