This is the information I used to setup my Allstar node 43943 on my 900 MHz repeater. This is no internet at the site and this is what I chose.

This hardware and software I used in this setup includes:

• Cudy LT500D 4G LTE Router
• Tello sim card with a 10 gb plan
• Zerotier VPN
• Raspberry Pi 3B+
• Hamvoip node image

ZEROTIER ON AN ALLSTAR NODE  from David KB4FXC

 Here are very steps to get setup on a HamVoIP nodes:

1)  Go to the zerotier website, register and activate an account. The website is here. Use the "Register" link:  https://my.zerotier.com/

2) Login to your new account and click the "Create a network" button. A new network with an arbitrary name will be created.

3) Click the link to enter the setup page for your new network. At the top 
of the webpage, you'll notice a 16 character (8 hexadecimal digits) 
network ID.  Something like "1c33c1ced0e4c478"  ....Make a note of this ID.

4) Now install the software on the HamVoIP node from the bash shell prompt:

pacman -Sy zerotier-one

5) Once the package is installed, run the zerotier daemon, which goes immediately into the background:

zerotier-one -U -d


6) From the HamVoIP node, join your new VPN network using the network ID 
noted above....For EXAMPLE:

zerotier-cli join 1c33c1ced0e4c478

*NOTE* that "1c33c1ced0e4c478" is an example...Use the network ID you got 
from the zerotier webpage, using your account.

7) The final step is to go back to the zerotier webpage and scroll down to the "Members" section and click the checkbox at the left to authorize the HamVoIP device, allowing it to join the network.

8) That's it!  Your VPN should now be on-line and running.  All your connected devices should show up on the zerotier webpage.

9) To launch your VPN when the node boots, just edit the
 /etc/rc.local file and place the command: 
"zerotier-one -U -d"  (without the quotes) just above the exit statement at the bottom of the file.  It automatically knows what networks to join.

I also needed to activate Zerotier on the router. Luckily it was easy as just adding the credentials into the field and ticking a box.

For an internet connection I chose Tello based on other peoples recommendations. I chose the 10 GB plan that they offered and it should be adequate for my application. I have a referral link, if you found any of this helpful and you and I can save some money. https://tello.com/account/register?_referral=P3R7086X

The only problem I am having at this time is that I am unable to have incoming connections. Some NAT-routers do not honor source-port preservation. Registration (by default) requires that the source port be preserved. The URL register.allstarlink.org expects the source port to be 4569 by default. With some NAT routers, source-port preservation is not guaranteed. This appears to be the case in my situation. Although I am showing up as registered on the servers, The status page shows that my node is not reporting.

My workaround is to spin up a HUB server at another location and just leave this node in that hub for incoming connections.

For remote administration I also added Zerotier to my Laptop computer. This way if I need to access the router or node remotely I first start my application, connect to my network, then I am directly connected to the equipment and can utilize Putty or WinScp. There is also an app for the phone you can use as well.