Failed to register pmm-agent on PMM Server: .

[root@XXXXX~]# pmm-agent --versionProjectName: pmm-agentVersion: 2.9.1PMMVersion: 2.9.1Timestamp: 2020-08-04 11:08:46 (UTC)FullCommit: f87359b1408887d014f88842d98c3bc7e6fe7d02[root@XXXXX ~]# pmm-admin config --server-insecure-tls --server-url=https://admin:admin@ local pmm-agent status…pmm-agent is running.Registering pmm-agent on PMM Server…Failed to register pmm-agent on PMM Server: .[root@XXXXX~]# docker psCONTAINER ID        IMAGE                       COMMAND                CREATED             STATUS              PORTS                                      NAMESf2c13d67c702        percona/pmm-server:latest   “/opt/”   6 minutes ago       Up 6 minutes>80/tcp,>443/tcp   pmm-server[root@XXXXX~]# netstat -na |grep 443tcp        0      0         ESTABLISHEDtcp        0      0         ESTABLISHEDtcp6       0      0 :::443                  :::*                    LISTENunix  3      [ ]         STREAM     CONNECTED     10474436 /run/systemd/journal/stdout

The graphana dashboard is live, but I can’t connect the percona cluster

FIrst thing I’d look at would be iptables getting in the way on your PMM server…I have a centos server that when I use port mapping (vs host networking) to the docker container I have to add an explicit iptables rule to allow traffic from the outside world to the docker0 adapter.  And mine also shows the port as open in listen.  
Here’s what I run  'iptables -I INPUT 10 -i docker0 -j ACCEPT" which the 10 just puts the rule before the last reject rule (10th line).  

[root@XXXXXdata_apps]# cat /etc/redhat-releaseRed Hat Enterprise Linux Server release 7.8 (Maipo)Firewall is not active.
Port 443 is active
[root@XXXXXXX data_apps]# netstat -na |grep 443tcp        0      0   *               LISTENtcp        0      0         ESTABLISHEDtcp        0      0         ESTABLISHED

[root@XXXXXXX~]# rpm -qa |grep pmm2-client-2.9.1-6.el7.x86_64pmm2-client-2.9.1-6.el7.x86_64

[root@scxxp0816cld ~]# ip addr1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00    inet scope host lo       valid_lft forever preferred_lft forever    inet6 ::1/128 scope host       valid_lft forever preferred_lft forever2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000    link/ether 00:50:56:90:06:10 brd ff:ff:ff:ff:ff:ff    inet brd scope global eth0       valid_lft forever preferred_lft forever    inet6 fe80::250:56ff:fe90:610/64 scope link       valid_lft forever preferred_lft forever3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default    link/ether 02:42:7a:51:58:bc brd ff:ff:ff:ff:ff:ff    inet brd scope global docker0       valid_lft forever preferred_lft forever    inet6 fe80::42:7aff:fe51:58bc/64 scope link       valid_lft forever preferred_lft forever - docker running and database percona (Master)