Thanks for your response.
We got this solved last Thursday, my bad for not updating my post.
The problem was True had blocked the IP address,
They had no reason to do so, we were not live streaming and our bill is paid online, never late.
The response we had from True was good once we were able to raise a ticket and their technician did confirm True had blocked the IP.
The security system technician stated this is a common problem and in his opinion was related to the shortage of IP addresses in Thailand.
Regardless, the problem is now resolved and we have, for the time being got our security cameras back online.
Thanks again for taking the time to respond.