Messages are taking too long to arrive

Problem description:
Messages are taking too long to arrive to it´s destination. Sometimes it takes more than 2 minutes for the other person to receive the messages, and when it does, it receives all at once, the same with me waiting for the messages. Do you know what might be the problem?
Error code/error message:
No code
What has been tried so far:
Restart the computer and the modem.
Messenger version:
8.5
Windows version:
10