MongoDB Connectivity Issue From last few days, I am facing connectivity issues with MongoDB Replica Sets deployed in google cloud. Interesting fact is these issues are appeared at Development machines and not on the production. Most common issues are:


Cannot connect to replica set "xxx"[xxx:27017]. Set's primary is
unreachable.
A primary with different host name [:27017] found in
server side. Different members found under same replica set name
"XXX"


These error are appeared frequently. How to resolve this?

Here is the screenshot of the error appeared:
As per Robomongo Tool error shows like that


  A primary with different host name [:27017] found in server side.
  Please double check if same host name and ports are used as in
  server's replica set configuration. If same set name is used for
  different replica sets, this configuration is supported only on
  different instances of Robomongo. Please open a new Robomongo instance
  for each replica set which has the same set name.


As per github blog documentation here it seems like the problem is Robomongo cannot learn the set name which is a critical information for connections to replica sets. 

For Example Workaround


Find a way to get your replica set name, something like rs-..., it
shows it in the URL
Close Robomongo
Open this file in your editor 


~/.config/robomongo/1.0/robomongo.json on macOS
C:\Users[your name].config\robomongo.json on Windows
~/.3T/robo-3t/1.2.1/robo3t.json on Linux

Search for the empty setName and add the replica set name there and
save the file
Start Robomongo again and it should work


For further your ref here