sql server 2008 r2 mirroring I am trying to set up mirroring between two servers behind the same firewall on the same subnet. 

I backed up mainserver and restored to mirrorserver.

I'm using the wizard on "mainserver" and connect to the "mirrorserver" using the sa login as both servers have the same sa login password.

The wizard creates endpoints on both servers correctly. When I start the mirroring it asks about FQDN but there is no domain so I click "Yes". It works for a while then I get the error alert below.

What is strange is that the error suggests it can't connect to itself.

Since posting this I found elsewhere suggestions that the problem is the database wasn't restored with NO RECOVERY on the mirrorserver. I tried this and now the wizard says 

Cannot connect to mirrorserver

Login failed for user 'sa'. (Microsoft SQL Server, Error: 18456)


previously

Alter failed for Database 'mydatabase'.  (Microsoft.SqlServer.Smo)

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

------------------------------

The server network address "TCP://mainserver:5022" can not be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational. (Microsoft SQL Server, Error: 1418)
This is typical Microsoft. The error message is about tcp ports. The actual error is that the mirror database wasn't restored with NO RECOVERY

BTW this is the best step by step guide I've found to setting up mirroring in a workgroup situation

Database Mirroring between a Server in Domain and Server outside domain (workgroup)