I am using a GL-B1300 as a essentially a VPN access point.
I am using a cable to go from the GL-B1300 into a hub, out onto my local wired network and into my Internet Gateway.
I am aware that VPN is not available unless the GL-B1300 is in Router mode.
And a cable must be in the WAN socket.
It's just a bit weird that I need a second cable from my network into the GL-B1300 in order to reach the GL-B1300's Admin Panel.
In the Internet | Ethernet section of the Admin Panel where I have assigned DHCP I see IP Address = 192.168.10.16. This, I believe, is the "external" IP of the GL-B1300. Can I open a port on the Firewall to see the Admin Panel from my Network?
In the Network | LAN section of the Admin Panel I can't change the RouterIP address because I get a message saying
"LAN subnet is in conflict with the WAN subnet, Please Change LAN Subnet to a different address." which is both reasonable and purely a feature of not allowing VPN in anything other than Router mode. Is there a way to set the "internal" IP to what I want?
Yep, you totally can, and it's recommended to do so because inserting a second cable which is connected to the same network (so WAN and LAN are the same) will cause routing loops and issues.
I don't remember the firewall settings for open access on WAN port completely, but I guess it was
setting zone WAN to allow instead of drop
creating firewall rule opening port 80/443 TCP to WAN side
All needs to be done in luci
Another method would be using goodcloud instead, if it's supported on that device.
Maybe a Simpler and More Secure Solution: Accessing Admin Panel via LAN Port directly
If you're looking for a way to access the admin panel of your VPN router, I may have a simpler and more secure solution.
For any future non-technical visitors to this topic. Try simply pluging a Laptop, PC or even a phone (with a USB-C to Ethernet adapter) into one of the LAN ports on your VPN router using a second Ethernet cable. This will give you a direct connection to the router's LAN interface.
Once connected, you can access the admin panel by typing the IP address assigned to the router (192.168.10.16 - in the OP's case) into a web browser. Alternatively, you can use SSH to access the router's command line interface:
ssh -oHostKeyAlgorithms=+ssh-rsa root@192.168.10.16
This method allows you to manage your VPN router without having to:
Configure the firewall
Use Luci
Expose the admin access to the wider network
And also avoid routing issues.