I have problems to connect to the remote service. How I could debug the networking issue?

There are few steps that could help to find the source of the problems. First we need to make sure that remote address is resolved correctly - we can use commands like nslookup & dig to resolve a host name to IP Address. If it's resolvable, we need to check that remote service is reachable - we can use tools like ping, traceroute, and related to check that network traffic is routed correctly. If it's not reachable, we need to check if routing is configured correctly and no firewall is blocking traffic between. If remote service is reachable, then we need to check if we can access the specific port on which service is listening - this is usually done with commands like telnet, nc and nmap. If port is not reachable, it's often happens when a firewall blocking traffic from external networks or traffic on non-standard ports.