• How you are trying to connect to your server. Write some details about your environment. Like Server OS, SQL Server Version/SP, [Server and client], Client tools you are using to connect.

    Is your server far from premises. what client software you are using to connect to SQL Server etc. Much environmental details may require to understand first.

    see furthermore here: https://www.mssqltips.com/sqlservertip/3114/sql-server-could-not-spawn-fruncommunicationsmanager-thread/

    Shamshad Ali