Balance 20X dropping pings on LAN

I have had a couple of clients that I have set-up their Balance 20X routers with separate physical VLANs for voice and data networks.
This was on firmware 8.2.0.
They have a Speedfusion tunnel back to our center here where we host their phone server.
We received a report of voice breakup and dropped calls.
Checking the tunnel health and logs, I did not see any issues. that would cause this.
A reboot would temporarily fix the issue, but it would always return.
I put up 2 separate pings going, 1 to the internal router IP through the tunnel, and another to a phone, plugged directly into the port of the router.
There were no drops on the internal router IP, but I was getting drops on the phone IP. This was the same for any phone IP I tried, through a switch or directly connected to the ports of the router.
We tried new phones and switches, as well as taking it down to only one phone, but the issue always came back.
We replaced the router, and that fixed the first client for good. I chalked it up to maybe 1 bad router.

I just had this happen again for another client, and we had to replace the router again. I am attampting to see if anyone else has had similar issues with any of these routers?
When checking, both of these routers were purchased off the same order back in March, so we are checking all routers now that were on this order.
Has anyone else had something similar happen, and did you find a fix for it?