I don't think backing up the panel, cold starting it, then reloading the database will help.

Pinging by IP address indicates there is at least connectivity between the computer and panel, but you need to be able to ping by name for a P2 Ethernet panel to connect (naming resolution needs to work).  If you're dealing with a system that uses DHCP, verify that the panel and/or PC are registering with DNS for that naming resolution.  Static IP addressing requires the use of the hosts file at the PC and manual entries in the Node Name Table at the panel.

While a firmware upgrade should not change any of the network settings, you might verify that the Node Name hasn't changed, the IP address is still assigned (with default gateway address set), all entries in the Node Name Table are still correct, and that the BLN/ALN name in the panel still matches with what is set in Insight or Desigo CC.

For a P2E panel, verify that TCP port 5033 has not been blocked.  For BACnet/IP, verify that UDP port 47808 (or whatever UDP port is in use) has not been blocked.  If the appropriate port is blocked, ping will still work, but you will not get the panel to connect to the front end.

In the event you are trying to get it online with Desigo CC (or will in the future), you still may have to migrate to a PXCM, PXCC, or PXC.A, since the vast majority of P2E & BACnet MEC's are not supported in Desigo CC.  (see attached)