After few test which we conducted, we came to a conclusion that MT doesn't free up RAM. This causes MT to crash after some time. Also after disabling firewall rules doesnt't free up CPU resources. Only deleting it does.
Bellow few examples:
What is intersting, although MT has some amount of free RAM resources, it crashes.
OSPF was enabled on this devices. End users were connected with pppoe, but this problem occured also without OSPF enabled.
We also made an experiment:
One MT was in AP mode, two other MT's were trying to establish pppoe session with non existing accounts. After one day MT, which was in AP mode, crashed. Time after which AP crashes depends on RAM and CPU speed installed.
We made this experiment using 3.30, 4.11, 5.0 firmware. The problem occures on all of them.
Many other companies has reported this problem to us.