After upgrade to 3.0 servers do not see each other

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Affected Roles: System Owner • System Administrator 
Related Nx VMS Apps: Nx Server • Nx Client
Difficulty: Medium
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It appears that under some very specific configurations servers in multi server systems might lost connectivity after upgrade to 3.0.

Issue description:

• During the upgrade from version 2.6 or lower no servers come up.
• In fact you can see that all of them are running and allow to connect directly with browser or Nx Client. All other servers at that moment are shown as "offline" in the resource tree.
• If you check "System Administration" menu(Ctrl+Alt+A), "Routing management" tab and click any offline server you'll see all network addresses with "0" port values like at the screenshot below:
  
  

Important Note! This article doesn't cover cases when some of the essential nodes just won't run after the upgrade. I.e. they are unavailable for the connection from local PC using browser thus blocking connectivity proxy for other hosts. Such issues should be addressed directly to our support staff.

It might happen if all your servers are located in plain local network and one of the following conditions is satisfied:

• Before the upgrade "Enable device and servers autodiscovery" option is off("System administration" -> "General")
• Multicast communication is intentionally disabled at your network on the networking hardware level by system administrators

We're going to improve Nx software so that such situations are resolved automatically during the database migration. Likely 3.1 version won't have such issue. But before that we suggest the guide to resolve the issue manually:

1. If you have autodiscovery option disabled -- please turn it on till servers find each other(typically happens within several seconds). To turn it on:
   - Go to "System Administration" menu(Ctrl+Alt+A)
   - At "General" tab, "System Settings" section find "Enable cameras and servers auto discovery" checkbox and fill it in
   - Click "OK" or "Apply" to save changes
   
   
2. If you already have auto-discovery enabled but there's still no communication and servers have "0" port values at the "Routing Management"  -- likely you have multicast connections disabled on the networking level. 
   No worries, there is an easy way to manually modify this port information:
   - Go to "System Administration" menu(Ctrl+Alt+A)
   - At the "Routing Management" tab click any "offline" server
   - Click "Add" button at the right panel, "Enter URL" dialog window will pop up
   - Input network interface address which is used for connection to other servers with correct TCP port specified to the URL bar(at the screenshot below my server uses 192.168.0.150 address, you need to input the corresponding one for your server; if port used in 2.6 version is different from 7001 you'll also have to specify it)
   
   - Click "OK" or "Apply" to save changes. Typically it takes seconds to get server back online