I found this over on the PiStar Forum and thought it would be of interest here.

https://forum.pistar.uk/viewtopic.php?f=11&t=1113&p=4456&hilit=ultimate+remote&sid=64ec5713dbeca9ce258e604c4665cd09#p4456

Ultimate remote dashboard access
Post by kb4aaa » Thu Dec 13, 2018 2:45 pm

After trying to get Zerotier to work on Pi-star image. I finally figured out what was blocking the pi-star web server. Now repeater operators or users can access your pi-star dashboard from any computer or device just like it was on your network at home.

quick and dirty instructions
setup a free account at Zerotier
SSH into your pi-star

(make system Read Write)
rpi-rw

(add zerotier port to pistar firewall)
sudo nano /root/ipv4.fw

# This line adds outgoing access to UDP/9993
iptables -A OUTPUT -p udp --dport 9993 -j ACCEPT # Zerotier outbound udp port

(to exit and save)
ctrl+x y enter

(restart pi-star firewall)
sudo pistar-firewall

(install zerotier)
curl -s https://install.zerotier.com/ | sudo bash

(install zerotier on startup)
sudo systemctl enable zerotier-one

(check status, should return 200 info [ID] [version] ONLINE)
sudo zerotier-cli status

(Join zerotier with your [network ID] listed in network on your account)
sudo zerotier-cli join [Network ID]

(refresh your network page on zerotier and check the enable access on your new connection you just setup)
(install zeroteir client on your pc,mac,linux,or smartphone)
(now you should be able access your pistar dashboard or SSH with the ip listed in your zeroteir network)

(make system Read Only)
rpi-ro


you now can SSH or access Pistar dashboard anywhere in the world without worrying about the ip address changing or forwarding ports from firewalls.