Unable to set static DHCP leases when using public IPs

If you want to set a DHCP static lease to a public IP then you will get the error 'Cannot use an address in this address range' and will be unable to set it.

It seems the web interface only allows RFC1918 addresses to be used as the 'Local IPv4 Address'

Hacking

A user reports success by getting the web interface to do some of the work, and then rewriting the configuration variables.

Using the web interface, attempt to enter all the static DHCP leases. Don't reboot after entering each one, hit Close and then add the next.

Now ssh to the router as user engineer and the admin password. Do

get InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPStaticAddress.

(note the trailing .). This should show the MAC addresses in the Chaddr fields, but with empty Yiaddr fields where the IP addresses should be. Now use the set command to enter the IP addresses, e,g.

set InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPStaticAddress.3.Yiaddr 81.187.xx.yy

Do the same for each static IP address required. Then reboot the router to make the changes active.

If you want to change the DHCP lease time to something different from 14400, the command is e.g.

set InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPLeaseTime 3600

Again, reboot to make change active.