We have set of 4G devices outside our network which gets into our network using Dynamic IP address.
Can we have monitor these devices or in other words whether APN network can be monitored.
NNMi can monitor devices using either SNMP or ICMP.
Now, it depends on your business needs and the capabilities of the devices on how you would like to monitor the nodes in your network.
For instance, if those AP can support SNMP communication, then it will be better to use that feature to monitor those devices (You might get more details on the component status of the APs).
In the other hand, if those devices do only respond to ICMP, then NNMi will monitor them for UP/Down status.
I hope that helps to respond your doubts.
Finally, you can always check the device matrix in the Device Driver Pack of NNMi to see if and what type of support does NNMi has for those APs.
All the best,