Why do I sometimes get checking server message when trying to text?

My S8+ gives me the message every once and awhile. Why?

Welcome to Android Central! Probably an issue with the network. Have you asked your carrier about it?

This seems to be a popular problem with no solution.

Posts say uninstall, but you can not uninstall Message+.

Tried disabling, but did not help.

Verizon support has no answers either.