Night hawk MR2100 connecting to router as backup WAN

So I've just received a new MR2100 and everything works well.  I'll use it as a mobile router, but also when at home I will connect it to my Synology router that has 2 WAN ports and use it as a failover for the main connection I have,

To do this, I understand I need to use IP passthrough, which will disable the wifi.

First question - is there a quick way to disable / enable IP passthrough from units trouchscreen? Or do I have to connect via the web interface everytime?

I've given the MR2100 an IP address of 192.168.5.1 with a DCHP range 192.168.5.2 - 99; my Synology router is on the subnet 192.168.1.0/24, therefore:

Second question - do I have to disable DCHP on the MR2100 prior to connecting it to the Synology router?