SM with NAT - DHCP Problems to customer router

This is an issue that's plagued me for years, curious if anyone else has the problem or knows a fix. My gut tells me it's a Cambium problem, hopefully someone can chime in. 

Assigned IP Address Hardware Address Lease Remained/State 000000000000 Used 

PktXmt Count: 4
PktRcv Count: 21
PktToss Count: 0

Generally it will lease, then shortly after it'll throw all 0's for the MAC & State changes to USED. It seems to happen with many types of router mfg/model, haven't come across any real pattern. In this state, customer can't pass traffic

Our current workaround is to set the customer router WAN interface to static with that address, but that isn't a long-term solution (should they reset their router etc). 

When I've seen this "problem", it turns out that another device on the customer network has that ip hard coded.

The IP is in "Use(d)" therefore the SM can't lease that IP as there is a conflict.

How many IPs do you have set up for lease?

I normally only lease one IP - Sometimes the customer tries to get creative, putting a switch between the SM and router - Seen this twice - When the particular device they are working with doesn't surf, they copy the settings on the router and - Well, you know the rest. 

You can either try to track down the offending device (the customer hardly ever admits "tampering") or set the SM to lease more than one IP to confirm.  You'll then have to go out and verify proper installation.  This is the only scenario I've ever seen this happen - YMMV

Good Luck