SM http lockup on SM with V9

I just installed a customer with an SM using NAT and PPPoE for the first time. After a week, they called and said they lost internet access. On my end, I could ping the unit and collect SNMP data, but I couldn’t get to the radio web page. I had the customer power-cycle the radio and operation returned to normal. Anyone else have this happen? Is there some NAT/PPPoE config I screwed up or should I avoid it?