After plan downgrade T3200M modem/wan IP isn't public

[tbor]

So, a couple days ago I was downgraded from a bonded copper Internet 75 plan to single copper Internet 25 as that's the maximum allowed under the Internet for Good program. Prior to the downgrade I had no issues and for the context of this post no issues with port forwarding.

Now that I'm on Internet 25, the modem ip address is showing up as 100.81.xxx.xxx which to me indicates that I'm being natted (as 100.64.0.0 - 100.127.255.255 = carrier grade nat addresses). I've called tech support 3 times and each time I'm told that 100.81.xxx.xxx is a public address, and that residential accounts all have public addresses. On two occasions the tech support agent spoke to their internal network support agents and they had indicated that this was indeed a public address and nothing is wrong. However, the outside internet can't communicate with a 100.81.xxx.xxx address, thus breaking port forwarding for my security camera and disallowing friends to connect to me for games I host with them.

For fun, I decided to plug the second phone line into the t3200m and when I do that I get a real public ip for the modem. The problem with that is when trying to use the internet it keeps forwarding me to registerdevice.telus.com and then errors out. I assume that line is also not meant for use as it negotiates with DMT to give me 3 down and 0.8 up instead of VDSL2 with 40 down and 7 up that the primary line enjoys. (Both lines are capable of 55/10 and would negotiate at 44/10 on the bonded 75 plan.)

I've reset the t3200m to default at least 5 times and left it unplugged overnight to force an IP change, however it still keeps receiving a 100.8x.xxx.xxx address. I even bridged port one and connected another router and it too received a 100.8x.xxx.xxx address.

I should note while the modem ip is 100.8x.xxx.xxx, whatismyip.com shows me a proper public ip address. When I enable WAN PING RESPOND I can ping that proper ip address from a command prompt locally, but I cannot from anywhere else on the internet. When I disable WAN PING RESPOND I can no longer ping said proper ip address. It's like the modem is grabbing an internal 100.8x.xxx.xxx address and also the proper public ip address but somehow only binding the internal one to its wan interface, if that makes any sense.

Because the second line gets a real public IP, I assume the t3200m isn't at fault and that this is either some strange misconfiguration on the primary line or perhaps Internet for Good clients are being natted.

Does anyone here have any ideas on this? Thanks in advance!