Hi Nirav,
Was there some change in the host/services-file or network configuration?
Check the /etc/hosts and /etc/services entry and check the result of uname -n, if this is "consistent".
Also check niping -v -H localhost, it should be consistent as well.
Also check your profiles for the host/port/services definition.
I'm curious why it is trying to use port 3900, because Dispatcher usually uses 32NN and Message Server 36NN. I saw also in your case, you are using CI with 01 (DVEBMGS01)? There are some "mixed" stuff here I think.
And check also R3trans -d to see if it does connect to the database successfully.
-->Earlier, validating the profile failed, see INSTANCE.OUT (/usr/sap/PRD/SYS/profile/PRD_DVEBMGS01_dbciPRD)
-->NiPConnect: 192.168.0.15:3900: connect (239: Connection refused)
-->NiBufConnect to dbciPRD/3900 failed (rc=NIECONN_REFUSED)
I hope this will help you.
Regards,
Andre