@waterchill 

Hi, thank you very much for posting on TP-Link Community.

Please check Internet IPv4 address on Advanced->Status->Internet part to see if it is a public IP or not, if not, it means you are behind a CGNAT, that is why remote web login or VPn doesn't work.

In addition, MR550 supports Tether App remote management, you could go to Basic->TP-Link Cloud page to bind your MR550 to your TP-Link ID, then login Tether App with the same TP-Link ID, when you are in a different network, as long as your phone and the MR550 are still online, you will be able to manage the MR550 via the Tether App remotely.

  @waterchill 

Please refer to this guide: How to troubleshoot if remote management does not work on LTE Gateway Router with 3G/4G Router mode

If you still would like to use the remote web management but Internet IPv4 address is not public, you will need to contact your ISP to see if they could assign you a public IP address.

Methods to tell whether it is a public IP address or not:

1) Private IPv4 addresses have the following class configurations:

Class A IP addresses: from 10.0.0.0 to 10.255.255.255

Class B IP addresses: from 172.16.0.0 to 172.31.255.255

Class C IP addresses: from 192.168.0.0 to 192.168.255.255

2) Apart from the private IP addresses in the above 3 classes, there is another range of IP addresses, which looks like a public IP address, but Carrier Grade NAT (CGNAT) address. They are from 100.64.0.0 to 100.127.255.255, which are usually not real public IP address either.

3) Or you could also check your real public IP address on “https://www.whatismyip.com/” website on a client device connected to the LTE router, then compare it with the 4G Internet IP displayed on Status page of its web interface. If they are the same, it means the 4G internet IP on the LTE router is a real public IP address, if not, it means it is private IP address or the CGNAT address.