Can I suggest you post your scenario to https://www.percona.com/forums/questions-discussions/percona-monitoring-and-management/ and we can take a look?

when trying to add the agent following the above commands
how can 443 work when container is initially configured to run on port 80??
port 80 doesnt work either though nor does without any port
how to proceed?

pmm-agent setup –server-insecure-tls –server-address=http://172.16.127.82:443
Checking local pmm-agent status…
pmm-agent is running.
Registering pmm-agent on PMM Server…
Failed to register pmm-agent on PMM Server: Post https://http:%2F%2F172.16.127.82:443/v1/management/Node/Register: invalid URL port “//172.16.127.82:443”.
root@ubu1804template:~# pmm-agent setup –server-insecure-tls –server-address=http://172.16.127.82
Checking local pmm-agent status…
pmm-agent is running.
Registering pmm-agent on PMM Server…
Failed to register pmm-agent on PMM Server: Post https://http:%2F%2F172.16.127.82/v1/management/Node/Register: invalid URL port “//172.16.127.82”.
root@ubu1804template:~# pmm-agent setup –server-insecure-tls –server-address=http://172.16.127.82:80
Checking local pmm-agent status…
pmm-agent is running.
Registering pmm-agent on PMM Server…
Failed to register pmm-agent on PMM Server: Post https://http:%2F%2F172.16.127.82:80/v1/management/Node/Register: invalid URL port “//172.16.127.82:80”.

this is how it looks on the dockerhost
root@t-pmm-sv-01:~# netstat -tulpen
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 0.0.0.0:9000 0.0.0.0:* LISTEN 0 727048 1959/docker-proxy
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 0 725319 2251/docker-proxy
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 101 19161 827/systemd-resolve
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 0 22712 1191/sshd
tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 0 727296 2237/docker-proxy
udp 0 0 127.0.0.53:53 0.0.0.0:* 101 19160 827/systemd-resolve
udp 0 0 172.16.127.82:68 0.0.0.0:* 100 564878 782/systemd-network