Since sapwalk it taking 2 days, there is no way snmpcollector will be able to monitor that device.
Hard to imagine any network admin would let one of their devices be that slow so a good starting point is the connection to it.
Remote into the system hosting snmpcollector and use 'pathping' to the device, or some other such tool.
Wireshark is another good tool for troubleshooting network problems.