The error message “cannot communicate with server” can be seen when logging into Cisco Jabber for a number of reasons. I have just recently implemented Cisco Expressway MRA and by troubleshooting this error message I was able to document possible solutions to share with you in case you encounter a similar issue.
These troubleshooting steps documented below will be purely on the basis that the user is able to login to Jabber from inside the corporate LAN but cannot when logging in externally. This is where I had most of my grief when setting up Cisco Jabber MRA.
Before you start, visit my article Installation and Configuration of Cisco Expressway C & E to use this as a checklist to confirm the correct setup. You might find there may be a simple but crucial step missing.
Possible Solutions to the error message “cannot communicate with server”
Use Cisco’s Collaboation Tools to Check connectivity
This can be a very handy tool to check and troubleshoot connectivity. CollabEdge validator helps deploy and troubleshoot Mobile and Remote Access feature. It simulates a Jabber login towards your Unified Communications Manager and IM & Presence servers through the Expressway-Edge. The tool will identify issues with your set up. Details about each issue will be displayed along with a corrective action plan.
Verify that DNS is set up Correctly
Use NS Lookup to verify that the collab-edge.tls.company.com SRV type DNS record is present.
Ensure that the Cisco Expressway-Edge server’s FQDN name matches exactly the value created in the collab-edge SRV record.
Verify that the corporate firewall has a rule for port 8443 that forwards traffic to the DMZ LAN interface of the Expressway-Edge server. Not recommended but open the rule for a very short while to see if this is the issue. If you still cannot connect then you can continue to trouble shoot a different angle.
Check your Traversal Zone between your Expressway C and Expressway E is Up
Log into both the internal and external expressway servers and ensure that both traversal zones are active and reachable.
Firstly – Verify that the Expressway-Edge server is reachable. Then verify the Cisco Expressway-Core server is reachable.
Lastly verify that Unified Communications status on Cisco Expressway-Core is enabled and configured.