JTAPI application used by customer. When checked it is not DEVConnect certified.
From the logs, we could see multiple disconnections with the JTAPI application.

Client uses jtapi-sdk-8.1.0.0.0.9

<133>Jan 8 02:16:46 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 590 1 com.avaya.aes | SECURITY:FYI:ClientHandler::streamClosed():user jtapilogger with IP Address 10.124.1.172 disconnected from driver service AVAYA#CM#CSTA#TPCAIAVAYAAESPR
<133>Jan 8 02:16:46 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 814 1 com.avaya.aes | SECURITY:FYI:tsviAuthenticateSession:user jtapilogger logged in to AVAYA#CM#CSTA#TPCAIAVAYAAESPR from 10.124.1.172 successfully
<133>Jan 8 02:18:13 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 399 1 com.avaya.aes | SECURITY:FYI:ClientHandler::streamClosed():user jtapilogger with IP Address 10.124.1.172 disconnected from driver service AVAYA#CM#CSTA#TPCAIAVAYAAESPR
<133>Jan 8 02:18:13 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 513 1 com.avaya.aes | SECURITY:FYI:tsviAuthenticateSession:user jtapilogger logged in to AVAYA#CM#CSTA#TPCAIAVAYAAESPR from 10.124.1.172 successfully
<133>Jan 8 02:26:00 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 631 1 com.avaya.aes | SECURITY:FYI:ClientHandler::streamClosed():user jtapilogger with IP Address 10.124.1.172 disconnected from driver service AVAYA#CM#CSTA#TPCAIAVAYAAESPR
<133>Jan 8 02:26:00 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 845 1 com.avaya.aes | SECURITY:FYI:tsviAuthenticateSession:user jtapilogger logged in to AVAYA#CM#CSTA#TPCAIAVAYAAESPR from 10.124.1.172 successfully

From mvap.logs, I could see:

<132>Jan 8 02:18:13 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 400 1 com.avaya.aes | ERROR:WARNING:TSERVER:ClientHandler.cpp/769 10 SendMsg(): getpeername() failed for socket -1, errno=9
<132>Jan 8 02:28:24 tpcaiavayaaespr TSAPI[21639]: +02:00 2020 962 1 com.avaya.aes | ERROR:WARNING:TSERVER:ClientHandler.cpp/769 10 SendMsg(): getpeername() failed for socket -1, errno=9

From messages:
Jan 8 02:26:00 tpcaiavayaaespr nslcd[6779]: [62c023] <authc="jtapilogger"> ldap_result() failed: Can't contact LDAP server

From JTAPI logs:
At the application that uses jtapi-sdk-8.1.0.0.0.9, the connection down is reported and no exception before that.
2020-01-08 16:19:40.678 ERROR 1389 --- [pool-92-thread-3] g.b.s.j.jtapi.JTapiProviderListener : Provider Shutdown event received. [ProviderEvent. ID: 114 - ID Name: Undefined Cause | Cause: 100 - Cause Name: CAUSE_NORMAL]
2020-01-08 16:19:40.678 INFO 1389 --- [pool-92-thread-4] g.b.s.j.jtapi.JTapiProviderListener : Provider Transmission-Ended event received. [ProviderEvent. ID: 112 - ID Name: Undefined Cause | Cause: 100 - Cause Name: CAUSE_NORMAL]
2020-01-08 16:19:40.678 ERROR 1389 --- [pool-92-thread-4] g.b.s.jtapilogger3.jtapi.JtapiProvider : Connection down. Attempt to reconnect
2020-01-08 16:19:40.944 INFO 1389 --- [pool-92-thread-4] g.b.s.jtapilogger3.jtapi.JtapiProvider : Provider connected! Provider state [17]
2020-01-08 16:19:40.945 INFO 1389 --- [pool-92-thread-4] g.b.s.jtapilogger3.jtapi.JtapiProvider : Got CallCenterProvider
2020-01-08 16:19:40.949 INFO 1389 --- [pool-93-thread-1] g.b.s.j.jtapi.JTapiProviderListener : Provider Out-Of-Service event received. [ProviderEvent. ID: 113 - ID Name: Undefined Cause | Cause: 110 - Cause Name: CAUSE_SNAPSHOT]
2020-01-08 16:19:40.954 INFO 1389 --- [pool-93-thread-3] g.b.s.j.jtapi.JTapiProviderListener : Provider In-Service event received [ProviderEvent. ID: 111 - ID Name: Undefined Cause | Cause: 100 - Cause Name: CAUSE_NORMAL]
2020-01-08 16:19:41.051 INFO 1389 --- [pool-92-thread-4] g.b.s.jtapilogger3.jtapi.JtapiProvider : Provider heartbeat is enabled. Provider initial state [16]. Tsapi initial state [2]
2020-01-08 16:19:41.300 INFO 1389 --- [pool-92-thread-4] g.b.s.jtapilogger3.jtapi.JtapiProvider : Switch DateTime [Sun Jan 08 16:19:41 EET 120] - Software Version []

1) contact the vendor of the app
2) tends to mean you have network issues making the tcp connection unreliable... diagnose the network issue.

Hi John,

We also experience inconsistent event (in case of disconnect) with Avaya AES JTAPI e.g. if station1 and station2 are in call and anyone drops the call application shouuld receive connectionDisconnect & terminalConnectionDropped event for monitored station/s. But sometime application receives and sometime not.

Is there any link where we can find the open issues with AES platform?

Regards,
Umesh

Known product issues are published via Product Support Notices (PSN) available through the Avaya support port (www.avaya.com/support). If you have purchased an Avaya product (e.g. Applications Enablement Services) then you should have a sold to number and single sign on credentials, and be able to sign up for and look for PSN notices for AE Services through the support portal.

I would start by enabling TSAPI tracing and then reviewing the AES side logs regarding event notifications for the calls in questions.
https://www.devconnectprogram.com/site/global/products_resources/avaya_aura_application_enablement_services/support/faq/tsapi/index.gsp#10