Struggling to get client connected when plesk docker is involved

Description:

I’m stuggling to add a new remote service to a PMM instance hosted under Plesks Docker configuration.

Steps to Reproduce:

PMM Server components installed as a docker container under Plesk (pmm-server:2 with host data folder). Host is connected to the PMM instance as it also contains a MariaDB instance which we’d like to monitor, which is all working. Connecting a second remote PMM client on an external server seems not to be able to connect, but networking doesn’t seem to be the issue.

Version:

PMM 2.39.0

Logs:

Agent in debug mode

INFO[2023-08-18T09:53:04.987+01:00] Connecting to https://api_key:***@pmm.***:443/ ...  component=client
INFO[2023-08-18T09:53:05.003+01:00] Connected to pmm.***:443.      component=client
INFO[2023-08-18T09:53:05.003+01:00] Establishing two-way communication channel ...  component=client
DEBU[2023-08-18T09:53:05.003+01:00] Sending message (4 bytes): id:1  ping:{}.     component=channel
DEBU[2023-08-18T09:53:09.992+01:00] Closing with error: rpc error: code = Canceled desc = context canceled
failed to receive message
github.com/percona/pmm/agent/client/channel.(*Channel).runReceiver
        /tmp/go/src/github.com/percona/pmm/agent/client/channel/channel.go:220
runtime.goexit
        /usr/local/go/src/runtime/asm_amd64.s:1598  component=channel
DEBU[2023-08-18T09:53:09.992+01:00] Exiting receiver goroutine.                   component=channel
ERRO[2023-08-18T09:53:09.992+01:00] Failed to establish two-way communication channel: context canceled.  component=client
DEBU[2023-08-18T09:53:09.993+01:00] Connection closed.                            component=client
PMM Host Nginx Logs

0.0.0.0 - api_key [18/Aug/2023:09:53:03 +0100] "POST /agent.Agent/Connect HTTP/2.0" 499 0 "-" "pmm-agent/2.39.0 grpc-go/1.57.0-dev"
0.0.0.0 - api_key [18/Aug/2023:09:53:09 +0100] "POST /agent.Agent/Connect HTTP/2.0" 499 0 "-" "pmm-agent/2.39.0 grpc-go/1.57.0-dev"
0.0.0.0 - api_key [18/Aug/2023:09:53:16 +0100] "POST /agent.Agent/Connect HTTP/2.0" 499 0 "-" "pmm-agent/2.39.0 grpc-go/1.57.0-dev"
0.0.0.0 - api_key [18/Aug/2023:09:53:24 +0100] "POST /agent.Agent/Connect HTTP/2.0" 499 0 "-" "pmm-agent/2.39.0 grpc-go/1.57.0-dev"

Expected Result:

PMM agent connects and feeds data in from remote host

Actual Result:

Errors as described above

Additional Information:

I did try to add the gRPC pass-through rules as described in Pmm-agent can not connect to pmm-server when using reverse proxy, but this doesn’t seem to have made anything happen.