I have Nextcloud 18.0.4 installed on Ubuntu 18.04 as a snap, with nginx as a SSL proxy, and forwarding it unencrypted to localhost:81. I can login fine from the web, but when I try to connect the iOS app, it says
It is not possible to connect to the server at this time.
The web login method doesn’t work because the Log in/Grant access (app token method) button simply doesn’t work.
I ran nextcloud.occ log:tail but no new log errors came up. I have no idea how to troubleshoot this.