Computer #1 has the database file and has shared the folder.
Computer #2 has a drive mapped the the database file on Computer #1.
If Computer #1 has a user logged in, while in Multi User Mode, Computer #2 receives a communication error H202.
Computer #2 can access and open the database file in Single User Mode when the User on Computer #2 is not logged into the database.
Computer #2 logs into the database and tries changing to Multi User mode and receives a "Cannot access the database" error, while Computer #1 has no user logged in.
I have run the "quickbooks connectivity tool", and it did not help.