I placed my installation behind a nginx reverse proxy, everything works fine but i cant get my theming, if i go back to the installation without the proxy the theming is fine, but as soon as I open the site behind the proxy I lost all the theming.
Any ideas ?
I was having the same issue and was able to solve it with help of the community using the overwritewebroot config param in nextclouds config.php.
Take a look at this: https://docs.nextcloud.com/server/17/admin_manual/configuration_server/reverse_proxy_configuration.html?highlight=overwrite#overwrite-parameters
I set the value of overwritewebroot to the path relative from nginx to nextcloud, which is in my case 'overwritewebroot' => '/nextcloud',
'overwritewebroot' => '/nextcloud',
It has been quite a while since you asked the question, so probably you have found another way to deal with it, but maybe someone else will find this answer helpful.