You might experience connection problems between machines and Horizon Connection Server instances.

Problem

If connectivity between a machine and a Connection Server instance fails, you see one of the following messages in the event database.

  • Provisioning error occurred for Machine Machine_Name: Customization error due to no network communication between the Horizon Agent and Connection Server

  • Provisioning error occurred on Pool Desktop_ID because of a networking problem with a Horizon Agent

  • Unable to launch from Pool Desktop_ID for user User_Display_Name: Failed to connect to Machine MachineName using Protocol

Cause

The connectivity problems between a machine and a Connection Server instance can occur for different reasons.

  • Lookup failure on the machine for the DNS name of the Connection Server host.

  • The ports for JMS, RDP, or AJP13 communication being blocked by firewall rules.

  • The failure of the JMS router on the Connection Server host.

Procedure

  • At a command prompt on the machine, type the nslookup command.
    nslookup CS_FQDN

    CS_FQDN is the fully qualified domain name (FQDN) of the Connection Server host. If the command fails to return the IP address of the Connection Server host, apply general network troubleshooting techniques to correct the DNS configuration.

  • At a command prompt on the machine, verify that TCP port 4001, which Horizon Agent uses to establish JMS communication with the Connection Server host, is working by typing the telnet command.
    telnet CS_FQDN 4001

    If the telnet connection is established, network connectivity for JMS is working.

  • If a security server is deployed in the DMZ, verify that exception rules are configured in the inner firewall to allow RDP connectivity between the security server and virtual machines on TCP port 3389.
  • If secure connections are bypassed, verify that the firewall rules allow a client to establish either a direct RDP connection to the virtual machine on TCP port 3389, or a direct PCoIP connection to the virtual machine on TCP port 4172 and UDP port 4172.
  • Verify that exception rules are configured in the inner firewall to allow connections between each Security Server and its associated Connection Server host on TCP port 4001 (JMS) and TCP port 8009 (AJP13).