I've got an Atlas 550 that is handling SS7 links for one of our service areas. Approximately every 15 hours this device reboots.
I'm on the C.9.3 firmware. The reboot reason is "out of memory" and the manuals all show the activity log error message showing "Ethernet driver out of memory" but there is no recommended fix (that I can find).
The ATLAS is susceptible to Ethernet traffic, even if it is not intentionally "malicious". It processes all Ethernet traffic it receives, even if it is not the destination IP address. The best option is to isolate the ATLAS as best you can (i.e. put it on it's own VLAN if possible to limit the traffic it receives).