Debugging Traefik when the Site Cannot Be Reached from outside Company's Intranet - docker-compose

Question

Using docker-compose I have deployed a web application that uses Traefik as the reverse proxy, listening on port 80. This works without problem when I'm inside my company's intranet. Outside of the intranet, however, I get a 'site cannot be reached' response. Pinging the address from outside shows that the address is reachable and port 80 is open.
I've also tried to use segments in my Traefik configuration to route both the internal and external hostname I have been provided but this has no effect:
version: "3.5"
services:
test:
image: emilevauge/whoami
deploy:
labels:
traefik.enable: "true"
traefik.foo.frontend.rule: "Host:${HOSTNAME};PathPrefixStrip:/test"
traefik.bar.frontend.rule: "Host:${EXTERNAL_HOSTNAME};PathPrefixStrip:/test"
traefik.port: 80
networks:
- frontend
...
I have configured the access logs to see if my requests are reaching Traefik, can anyone advise me what I should be looking for and how to filter the huge amount of text produced to find it? This is my Traefik setup configuration:
version: '3.5'
services:
traefik:
image: traefik:alpine
command: |-
--entryPoints="Name:http Address::80"
--entryPoints="Name:https Address::443 TLS"
--defaultentrypoints="http,https"
--acme
--acme.acmelogging="true"
--acme.domains="${HOSTNAME}"
--acme.domains="${EXTERNAL_HOSTNAME}"
--acme.email="${ACME_EMAIL}"
--acme.entrypoint="https"
--acme.httpchallenge
--acme.httpchallenge.entrypoint="http"
--acme.storage="/opt/traefik/acme.json"
--acme.onhostrule="true"
--docker
--docker.swarmmode
--docker.domain="${HOSTNAME}"
--docker.network="frontend"
--docker.watch
--api
--api.statistics
--logLevel="DEBUG"
networks:
- frontend