LILIN Dvr

[mutanti]

Have a few clients who have the LILIN Dvr units installed and have been asked to get their phones working. 1 In particular have been having issues getting it working correctly.
I have Set IP address Of DVR at 192.168.1.180 ( Modem Range set to 192.168.1.100 to 192.168.1.199
Cameras are at 192.168.1.181 to 192.168.1.189
Gateway to modem on 192.168.1.1
Port changed from 80 to 8080
Have changed the default password on the DVR...

Modem Ip 192.168.1.1
Have done the port forwarding accordingly.
Have even tried to Set the DMZ on the Modem for the DVR
TP-Link Modem ( First Modem was a Netgear with same issues )

They have a Static IP Address.
in the Lilin App on Phone have the Static IP address , Port Username and password. ( Wifi Off on phone )
Some cameras will show 1 minute and then not the next.
sometimes 6 cameras manage to show on the app and others none at all.
checking each camera when i run the test it will sometimes show the camera and other times wont.
I have tried different ports, Different Modem and changed the DVR IP several times all with the same issue. DMZ the DVR IP and so On..
When I run a check on the port in canyouseeme.org it shows the port working one minute then blocked the next, - seems to alternate from available to blocked. ????
Rang Telstra who say they are not blocking any ports.
Tried the DVR at a different location and it worked fine ( Changed the Settings to reflect the Different Modem )

So What am I doing wrong - It seems to work very slowly or when I test will show a camera 1 moment and not the next.....
Have not been a fan of the LILIN DVRs with the several I have setup although the Quality appears good.
Have Removed obvious details from Image below.