4g modem in Ubuntu 18.04, why did the internet disappear?

Question

ubuntu

Good day. I connected the unlocked Huawei E3272 modem with the MTS SIM card to Ubuntu 18.04 and the Internet appeared immediately. The next day, through dancing with a tambourine, Network Manager was installed and the Internet was gone. The interface appears, the IP is assigned, the routes are correct. When you try to ping, for example, Yandex, 100% loss, although the IP is determined, apparently DNS is working. When pinging on 8.8.8.8 the same situation, 100% loss. How can I solve the issue WITHOUT uninstalling Network Manager? (If that's the case at all)