If supported by the device, put the TP Link router in Bridge Mode. This disables the routing capability, effectively turning it into a switch + WiFi access point. All routing, addressing, etc will be handled by the Netgear.
If you are using the mobile network for Internet access you may run into other issues.
Many mobile carriers now use Carrier Grade NAT to handle IPv4 addressing. The three major US carriers, Verizon, AT&T, & T-Mobile, all use CG-NAT in their mobile networks (a Google search for “AT&T mobile CGNAT” etc provides many links to confirm) .
CG-NAT does not support port forwarding, so it prevents remote access for services such as Plex. You can still access Plex remotely via Plex Relay, but the service will be limited to 2 Mbps (1 Mpbs w/o a Plex Pass).
Your carrier would need to provide you with a publicly reachable static IP address that supports port forwarding, and not all provide this capability.
There are several threads on the forum regarding Plex and CG NAT. This one has a good discussion of the issue and possible resolutions: How to Setup Remote Access with CGNAT & Static IP Address .
https://support.plex.tv/articles/200931138-troubleshooting-remote-access/
