Have you ever wondered why your port forwards and dynamic dns solution doesn’t work on 4G? The answer is carrier NAT or CGNAT for short.
CGNAT is a tool mobile networks use to share a range of IP addresses with multiple users, so you could have 1000 mobile users sharing 250 public IP addresses at the same time. They can do this by hosting the public IP in their core networks so the IP on your 4G router isn’t the public one but rather an internal carrier IP. So when you set up your port forwards on your router you aren’t forwarding traffic from your actual public IP.
The solution to this problem is to use an i-spi by Netcelero. The i-spi can provide you with four port forwards on a static IP.