I have had no problem using ISPConfig as a reverse proxy for IPv4 addresses under Sites/Redirect with Redirect type set to proxy and the path to http://xxx.xxx.xxx.xxx/. But I can't get it to accept IPv6 addresses in standard form like http://[2a00:1450:4009:818::200e]/. It just throws a red banner error. Are only IPv4 addresses accepted or is there a way?
Seems to be not accepted as valid input. I've tried several formats. You should be able to create a workaround by using a hostname and link that to the ipv6 addresses by either a dns entry or by adding it in your (web)server's /etc/hosts file.
Brilliant!!! Using the hostname worked. I had earlier used the domain in /etc/hosts but that just caused infinite redirects. I now have a Mastodon server proxied through ISPConfig via IPv6. This also required fixing nginx proxy on the Mastodon server to kid Mastodon that a http request was actually https. See https://blog.vyvojari.dev/mastodon-behind-a-reverse-proxy-without-ssl-https/
