The best firmware version for Molec series cameras is V2.800.
3DNR and 2DNR of V2.820 cause more noise.
Once upgraded to V2.820, it is difficult to downgrade back to the old firmware.
Try this Upall_IPC-HX2XXX-Molec
Dahua Upall is a complete recovery firmware.
But I don't know how to use.
Maybe...