Heimdall webpage shows blank

I followed the guidance of link: SWAG setup - LinuxServer.io.

after implemented it, refresh web the content look like below:

my configuration of heimdall is below:

‘’’

version: “2.1”
services:
heimdall:
image: ghcr.io/linuxserver/heimdall
container_name: heimdall
environment:
- PUID=10xx
- PGID=10xx
- TZ=xxx/xxx
volumes:
- /srv/xxxxx/appdata/heimdall/config:/config
ports:
- 80xx:80
- 4xxx:443
restart: unless-stopped
networks:
default:
external:
name: SWAG_default
‘’’
when I use local lan IP to access it, the webpage shows normal.

Could someone share some experience about it?

I checked the log of the docker itself, there is no error report in it.