I have a reverse proxy with apache at send.furrysend.de
The application is Send https://gitlab.com/timvisee/send
The site works, but no files can be uploaded.
this is the message i get https://ibb.co/g74FCCw

this is my apache configuration file

<IfModule mod_ssl.c>
<VirtualHost *:443>

ServerAlias send.furrysend.de
ServerName furrysend.de

ProxyPass / http://185.216.179.27:xxxx/
ProxyPassReverse / http://185.216.179.27:xxxx/
ProxyPreserveHost on

SSLCertificateFile /etc/letsencrypt/live/send.furrysend.de/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/send.furrysend.de/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
</VirtualHost>
</IfModule>

i tried this, but it didn’t work. i may have used it incorrectly.
https://www.serverlab.ca/tutorials/linux/web-servers-linux/how-to-reverse-proxy-websockets-with-apache-2-4/

This could also help
https://gitlab.com/timvisee/send/-/issues/15