You don't need to open any port for Hubitat in order for it to work.
Maybe it was previously for reverse proxy or VPN? I would remove it if I don't know what's it for.
Ah - Insteon, blast from the past. I used to be a an Insteon devotee… actually found my way to HE salvation during the Insteon hub blackout a few years back. If there is any Insteon refugee support group count me in
Quick internet search brought me to that page. Didn't really read it, until sending it out. Finally scanned it and found where port was mentioned. No idea if it is even relevant or not.
I used to use Insteon before their corporate problems when I switched to Hubitat. I believe this was left over... I deleted it and confirmed that everything still works, including HD+
I was a early tester and proponent of the Insteon integration for Hubitat. Thanks to the work of two very talented people, the project became a reality. I have not used the Insteon app in years, so it really doesn't matter what happens with the company. Everything is fully local, and there are enough Insteon devices available to last me a lifetime.