From the gateway side, the operator issues a gray ip (192.168.127.0) by setting a specific apn. The provider's network is connected to the enterprise network through an optical media converter (10.10.10.2), and then through routers and switches (18.104.22.168) to computers and servers. The provider issues DNS servers, but they do not include the topology of the enterprise (hidden behind NAT). The routes are spelled out correctly, which is confirmed by tracing from the enterprise network to the gateway and vice versa. Also pass ping requests in both directions.
By DNS settings, I mean the DNS settings in the mobile interface settings, as well as the "DNS forwardings" setting.
We measure the difference by sending a request to a device connected to the rs485 interface of the gateway and receiving a response from it from a computer in the enterprise network. The difference between request and response is about 5 seconds on a network without DNS (ping 50ms).