Resolving Text Message Sending Issue on Huawei P10 Lite in Play Network

Hello. Recently, I have a problem, he doesn't always send text messages. The following message appears: The message could not be sent. I have a phone in the Play network.
I called the operator, they said to set the network selection from automatic to manual on the phone, so that only one network was searched.
On the Huawei website, they said, however, that it can not be done on Play, because it is invariably set to borrow from other networks as it has closer coverage
Has anyone set it up? I tried only 2G network and internal roaming: disable.

You go into Settings-More-Cellular-Operator.
And there turn off the automatic mode and you will be able to choose the network you want.

Have you installed the latest system update?
Recently, my P10lite lost coverage on my phone when I was using the Internet, but a recent update has removed this problem.