Try using ports 81 and 82. Also use different port for each camera.

If you type whatismyIP.com in your browser, you will see your service provider’s address to your modem. It is the IPv4 and the IPv6 numbers. If you know the address and port number you can use them...

NO-IP is free if you confirm your host name every 30 days. They send you an email warning that you need to take action. Each time they ask if you want to upgrade to the paid service. I have kept my...

After you reset the router to factory specs. the user id and password are both "admin". Many times it is printed on the bottom or back of the router.

You may need to update the firmware. https://www.tp-link.com/us/faq-781.html

see https://www.manualslib.com/manual/1239913/Tp-Link-M7310.html as it shows EU countries but not US. Not sure why. Also found this on an AT&T which uses the same type of system a T-Moble....