There have been no such changes as you mentioned. Could it be something else?

Latency in the network could make SNMP time out. You can increase the DFM SNMP timeout under DFM > Device Management > SNMP Config. By default, it is four seconds.

I have increased SNMP timeout to 10 seconds, but nothing changed.

For one device, I have noticed that it was moved from All Known Devices to All Questioned Devices when there is a network congestion and it stays in All Questioned Devices since.

There is a known bug where devices move into a Questioned state, but the reason is no SNMP Timeout. Those devices get put into the Questioned/Other state, and the cause is an internal error.

If the device says that SNMP timed out, you can start a sniffer trace filtering on udp/161 traffic, then try rediscovering the device.

Is there a sw patch for this bug?

Yuo can contact TAC to get it. The patch is a new DFMInChargeSubscriber.class.

I applied the patch, but now I am not able to remove/rediscover those devices. I did uncheck "Synchronize with Device Credential Repository" in Device Selector.

Delete the devices from DFM, and they should go into a pending state. Then, run:

pdterm InventoryCollector InventoryCollector1 TISServer DFMOGSServer Interactor Interactor1 NOSServer PTMServer

pdexec InventoryCollector InventoryCollector1 TISServer DFMOGSServer Interactor Interactor1 NOSServer PTMServer

That should purge the devices.

E:\PROGRA~1\CSCOpx\bin>pdterm InventoryCollector InventoryCollector1 TISServer D

FMOGSServer Interactor Interactor1 NOSServer PTMServer

ERROR: cmd failed. Server reason: One of the entries in a list of application n

ames to pdshow, pdexec or pdterm is invalid.

E:\PROGRA~1\CSCOpx\bin>pdexec InventoryCollector InventoryCollector1 TISServer D

FMOGSServer Interactor Interactor1 NOSServer PTMServer

ERROR: cmd failed. Server reason: Application InventoryCollector1 is not registe

red. All requests to operate on this application will be ignored.

Some devices have been moved back to Learning and then back to "All Questioned Devices in Inventory Services > Others (subcategory)"

Make sure the permissions on the patched file are correct, and that casuser has full access. Also, check with the TAC engineer to make sure you got a patch for DFM 2.0.

casuser has full access to the patched file. I told him that I have DFM 2.0.10 when I opened the case.