Communication link failure error message is shown due to various reasons. Follow any of the steps mentioned below to resolve the issue:
Insufficient user privileges:
Ensure that the user has sufficient privileges to access the MySQL database from the host where Applications Manager is running. Follow the steps mentioned in this link to resolve the issue.
Bind address mapping issues:
If you want to allow remote access to the MySQL server, implement the following change in my.ini or my.cnf file:
If you choose to specify a list of selected IP addresses, make sure that the IP address of the Applications Manager machine is also present in the list.
3. MySQL port is blocked by firewall/VPN:
Perform a telnet operation from the machine where the Applications Manager is installed. If any VPN or proxy is set to that machine, then make sure that the relevant IP (i.e. new IP after applying VPN) is also present in the bind-address list of IPs.