HAProxy
info
Also see pfSense and HAProxy
Below is a generic HAProxy config, using audiobookshelf.YOUR_DOMAIN.COM.
To use http2, ssl is needed.
global
# ... (your global settings go here)
defaults
mode http
# ... (your default settings go here)
frontend my_frontend
bind :443 name :443 ssl crt-list /path/to/cert.crt_list alpn h2,http/1.1
mode http
acl is_audiobookshelf hdr_beg(host) -i audiobookshelf
use_backend audiobookshelf_backend if is_audiobookshelf
default_backend default_backend
backend audiobookshelf_backend
mode http
server audiobookshelf_server 127.0.0.99:13378
backend default_backend
mode http
server default_server 127.0.0.123:8081