Hi Tom,
Could you run the below command and advise on the output?
$MDS_FWDIR/scripts/cpm_status.sh
Then if you run the following and advise on the output.
$MDS_FWDIR/scripts/server_status.sh
These 2 commands are essentially just checking to see if the server is up and running correctly. Take a look at "An error occurred while receiving the HTTP response to..." error when trying to log into R80.10 Sma... specifically the troubleshooting steps in the symptoms section.
Feel free to post the outputs of the tcpdump, netstat and log file entries from SOLR file.
If this is a production SMS, it may be an idea to raise a TAC case as that may be quicker to get a resolution.
Regards
Mark