CLOSE_WAIT pileup and Application Timeout

List,

I am facing a network (TCP IP connection closing issue) .

Running a mobile tablet application, Android application to update the
status of vehicles fleet say around 1000 numbers installed with the app on
each vehicle along with a vehicle tracking application server solution
based on Java and Wildfly with PosrgreSQL16 backend.

The mobile tablets are installed with the android based vehicle
tracking app which updated every 30 seconds its location fitted inside the
vehicle ( lat long coordinates) to the PostgreSQL DB through the java
backend application to know the latest location of the vehicle and its
movement which will be rendered in a map based front end.

The vehicles on the field communicate via 443 to 8080 of the Wildfly
(version 27 ) deployed with the vehicle tracking application developed with
Java(version 17).

* The mobile tablet communicates to the backend application over mobile
data (4G/5G SIMS). *

The running vehicles may disconnect or be unable to send the location
data in between if the mobile data coverage is less or absent in a
particular area where data coverage is nil or signal strength less.

The server on which the backend application runs most often ( a week's
time or so) shows connection timeout and is unable to serve tracking of
the vehicles further.

When we restart the Wildfly server the application returns to normal.
again the issue repeats after a week or two.

In the Server machine when this bottleneck occurs I am seeing a lot of
TCP/IP CLOSE_WAIT ( 3000 to 5000 ) when the server backend becomes
unresponsive.

What is the root cause of this issue ? Is it due to the android
application unable to send the CLOSE_WAIT ACK due to poor mobile data
connectivity ?

If so, how do people address this issue ? and what may be a fix ?

Any directions / or reference material most welcome.

Thank you,
Krishane