Cannot maintain connection (Zigbee 2.5)

I am unable to maintain the connection be tween my 2 Xbee Series 2 modules.

I had them set up in API mode, XB24-B firmware (Zigbee 2.5 coordinator and router/end device) to pass sensor information (just polling the IO pins). That worked, consistently for a week or so. I set it aside and went on with another part of my project. I came back to them today and the modules connect and sent data in choppy spats until finally it stopped completely. I re-flashed the firmware and then reset them from scratch. Nothing.

I just tried flashing XB24-ZB firmware (API coordinator and router) and got them to connect after resetting the router over and over for 30 minutes… I just reset it again to see if they would connect. Nothing.

*I kept all the settings the same as a couple weeks ago (when it worked flawlessly), except I disabled the sleep mode in the XB24-ZB router (SM = 0)

UPDATE

I think it was a buffer overload on the router. 4 analog inputs polling at 200ms it just too fast to tx. I set the polling time to 500 and it is already better.

Thanks for the follow up that you got this working.