Does the Nighthawk XR500 work with Express VPN?

I have had the XR500 for just over a year and a half or so and have really enjoyed it.  I then purchased a subscription to ExpressVPN becuase they specifically stated that they have software support for the NETGEAR Nighthawk series routers, but after purchasing the service, I discovered that they only full support a few router models, of which the XR500 isn't one of, and then told me that without the sponsored app / software installed on the router, it would not serve as anything other than a media streamer.  So no IP masking or DoS attack protection.  

Is it possible to effectively get these features on my router using the apps for the R7000 or R6700?  If there isn't a way to fix the issue, are there any recommendations for a compatable VPN service that will offer me the total coverage that I'm looking for?  I only see options for HideMyAss and PureVPN.   Is there a firmware update that expands this selection, or do I just need to buy a new router or different VPN subscription and get a refund from ExpressVPN?