HG659 Forgets Port Forward rules every few days

Hi all,

Having problems with a Voda supplied HG659 on a newly provisioned Fibre circuit (business)

We have 3 port forward rules set which seem to get forgotten by the router periodically causing problems primarily for our CCTV monitoring.

The process I use to create the rules is by logging in as Admin on the router, then find the Lan device by Mac address and assigning the port forward rule to it. It does work for a few days but then seems to forget it.

Is there some kind of config that is being pushed to the router by voda perhaps which is overwriting the config on the modem? Or something more benign such as me just not knowing how to create a port forward properly?

Thanks in advance,