Validating connection with URL [jdbc:sqlserver://xx.xx.xx.xx:1433;databaseName=ABC;selectMethod=cursor] failed: java.sql.SQLException:,Cannot create PoolableConnectionFactory (The TCP/IP connection to the host xx.xx.xx.xx, port 1433 has failed. Error: "connect timed out. Verify the connection properties. Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port. Make sure that TCP connections to the port are not blocked by a firewall.".)
Confirm you are using the correct driver for this db.
Check the connecting system (by that I mean the one with DB connect on it) to confirm it doesn't have a local firewall in the way.
Check the network between the two systems to confirm they don't have a firewall in the way.
So, some extra debugging tips for this:
First, if you can't connect to this SQL Server box with SQL Server Management Studio (SSMS) with these same settings, then jdbc has no chance of connecting either. But even if you can connect to it from SSMS, it is unlikely you are replicating all the networking between your actual DBXv2 box and the SQL box, so a firewall can still be in the way.
Second, double and triple check local firewall settings as well. I can't test this at the moment, but you might be able to telnet to the IP on port 1433 to confirm that at least you can connect out. I'm SURE it'll be either gibberish or blank nothing if you can, but it's worth a try to see if you can do it or if you get a "connection refused" or "connection timed out" or some other variant of "the network's stopping you, somewhere".
As a last resort, you COULD try sniffing packets via wireshark or tcpdump - that might tell you something about the traffic involved.
I hope this helps! If it does not, please provide more information about what you've tried, what other settings are in place, etc... It's hard to diagnose this with only the little information you provided - that's a jdbc error string, not actually a Splunk thing.