Iphone Mobile app breaks Nextcloud

Has anyone here experienced , running nextcloud behind nginx with letsencrypt , connecting the mobile app and immediately receive “Bad Gateway” error.

What was previously accessible from web is now dead in the water.

I can restore nextcloud from backup and everything is accessible again but is there something the mobile app changes on the server that would be creating this issue?

Thanks

Similar questions have already been asked and answered in the past. Please check-out if this helps you solving the issue:

https://help.nextcloud.com/search?q=bad%20gateway%20nginx

None of these address this issue that I found, they may be similar in that they receive the same generic “Bad Gateway” but none of them occur as a result of connecting to the site from the mobile app.