What are the problems when using WebRTC in mobile networks?

Question

WebRTC

Good afternoon!
I'm developing a WebRTC based application and I've come across this kind of problem. Cannot establish a P2P connection when using a mobile network.
Tested:
1. in the same PC-PC local area network, it works fine;
2. in the same local network PC-phone, also works;
3. in different subnets (both behind NAT) PC-PC works;
4. on different subnets (both behind NAT) PC phone (phone uses mobile internet), not working.
The question is, who worked with WebRTC, did you have any problems using the mobile Internet? What can they be connected with and are there any solutions? Or at least tell me where to dig.
This package is currently used for WebRTC: https://github.com/priologic/easyrtc