Help with Audiobookshelf Port Number

Simply put, I can't get Audiobookshelf to respond to any port other than 80. I'm using the following Docker Compose (spacing may be off because I suck at formatting posts):

version: "3.7"
services:
audiobookshelf:
image: ghcr.io/advplyr/audiobookshelf:latest
network_mode: "host"
ports:
- 13378:80
restart: unless-stopped
volumes:
- /media/Vault/ABS/audiobooks:/audiobooks
- /media/Vault/ABS/podcasts:/podcasts
- /media/Vault/ABS/config:/config
- /media/Vault/ABS/metadata:/metadata

The way I understand it, externally the host should answer on port 13378 and the container on port 80. Just for kicks, I've tried the following variations:

• 13378:80
• 80:13378
• 13378:13378

I've even tried it without the version statement. Regardless of these, Audiobookshelf will only answer on port 80. All my other containers work fine and answer on the port I designate.

I do not have anything else listening on port 13378.

What am I doing wrong?