How to resolve issues with the master-slave connection in Redis when they cannot connect?

There could be several reasons why the Redis master-slave connection is not working.

1. Network issue: Check the network connection for proper functionality, ensuring there is proper communication between the master and slave servers, which can be tested using the ping or telnet commands.
2. Configuration issue: Check if the configuration files of the master and slave servers are correctly set up with the master-slave relationship, including ensuring that the IP addresses, port numbers, passwords, and other information are accurate.
3. Firewall issue: Verify the firewall settings to ensure communication between the master and slave servers is allowed.
4. Check the status of the master and slave servers to ensure that the master server is functioning properly and able to accept connections from the slave server.

Solution:

1. Reconfigure the configuration files for the master and slave servers to ensure they are set up correctly.
2. Check the network connection to ensure it is working properly.
3. Check the firewall settings to ensure that communication between the master and slave servers is allowed.
4. Check the status of the master and slave servers to ensure the master server is operating properly.

If none of the above solutions work, you can try rebuilding the connection between the master and slave servers, or reach out to the Redis official or related technical support for assistance.