I have a similar issue to the RUT955 reported here
I am asking my device manufacturer to change their firmware to make a second DHCP server request after one minute if the first request fails.
If I have someone on-site, I can ask them to leave the RUT240 powered on but cycle the power on my unit to force a reboot and new DHCP request.
The device has a built-in watch dog, if it cannot make connection to our server for over 12 hours, it forces an automatic reboot. 12 hours can be a very long time with a nervous customer ;)
Is it possible to use VLAN over Remote Management Service (RMS) to manually disable the LAN port and then re-enable. That would trigger a new DHCP request from my device.
As the author of the RUT955 post suggested, it would be more "friendly" if the RUTxxx did not enable the LAN port until its DHCP server was ready.