the most easy solution would be: start anew by using nextcloudpi.com - a nice tool, especially for raspis and rookies.
it’s part of the official nc.versum.
is normally not encrypted. so maybe it’s good that your data can’t be reached.
what’s the exact error message?
did you test the connection with a default web page? just to make sure that your mobile browser can establish a connection to your raspbi.
and normally nextcloudpi is listening on port 80/443/4443 (and 80 is redirected to 443) did you change that? or i’m i wrong?
My router didn’t allow me to open ports 443 and 80 (that’s why i tried to use 8080) and I just found out why: the ports were already occupied by something else. Using these ports it works just as intended.