Nighthawk M1 MR1100 won't connect with Yale Smart Home Hub

[HimalayAir]

I've bought the M1 specifically to allow me to use a Yale Smart Home alarm system on a property with no cabled broadband connection.  The Yale Hub has to be connected to the router via Ethernet, not WiFi.  When I plug it into the M1, the connection LED on the Yale Hub turns green (showing it's connected) and the device shows up correctly when I use Netgear Mobile app to look at the network.  However, the Yale Smart Home app says that the Smart Hub is offline (and Yale Support can't see it online either)

I've tried the Yale Hub on two other networks (with other routers) and it all connects up fine - So Yale Support is saying that there can't be anything wrong with the Hub, and there must be an issue with the Router.  However, I've got three laptops, an iPad, two iPhones and an Airbook Pro all connected to the M1 Router - and they all work fine so there doesn't seem to be any issue with the M1 either.

It's just the two devices together which have problems.  Yale Support say it might be something to do with Port Forwarding or Blocking or DNS Settings but can't advise further as they're not network people and no-one else has reported this issue.  I've not done anything to the change the default settings on the M1.

Can anyone suggest a fix?  I'm relatively technical, but have limited understanding of Networking.

[W1lliam]

you can try to insert another Ethernet Switching HUB, any brand should do the work, between M1 and Yale Hub. Sometimes just hardware interoperability problem. 

William