Added 4 MySQL servers as clients but the PMM Metrics Monitor only shows one

Hi Milos , I am glad you were able to solve this, and yes I agree our Documentation is missing this important reference - the firewall mention is buried in our Glossary in the Ports section [url]Percona Monitoring and Management. I’ve submitted a ticket to improve Doc, thanks for reporting it!
[url][PMM-2099] Add mention of firewall ports to installation guide and in FAQ - Percona JIRA