Database Mirroring Error 1418 
Hello Everyone.
This post will be helpful in resolving the error 1418 that we may come across when tried to configure Database Mirroring between Primary and Secondary SQL Servers.
Error:
The server network address “%.*ls” cannot be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational.
To resolve this, we will have to restart the endpoints on the Principal (Primary) Server and proceed with enabling Database Mirroring again.
Please execute the below to check the Mirroring Endpoint Name and status of endpoints.
SELECT * FROM sys.endpoints
WHERE type = 4
Recycle the endpoint on the database mirror. To do this, follow these steps:
On the principal database, execute the following SQL script to stop the endpoint:
ALTER ENDPOINT <Endpoint Name> STATE=STOPPED
Execute the following SQL script to restart the endpoint:
ALTER ENDPOINT <Endpoint Name> STATE=STARTED
Note: If communication between the endpoints does not restart after you execute the scripts, execute the scripts on the database mirror.
However, the database may enter a "Suspended" state after you do this. If this issue occurs, execute the following SQL script:
ALTER DATABASE <Database Name> SET PARTNER RESUME
