Navigator.sendBeacon() different behaviour

I have two servers(machines) on which a Java application is hosted in each one of them.

In this Java app,a jsp is calling another jsp as below,

\ below function is inside abc.jsp function sessionMark() {
navigator.sendBeacon(‘logger.jsp’);
setTimeout(sessionMark, 2 * 60 * 1000 );
}“
Both the servers have same configurations of basic ldap authentication.

It was working before. But observing this logger.jsp failing recently.

Also, the other jsp calls on abc.jsp page are all working and they are using ajax like below.

$.ajax({ url: "VO.jsp", type: 'POST', data: {scripts:scripts,on: 'true',tb:'yes',}, success: function(data) { //do something } });

when accessing the app in one of these servers, logger.jsp is giving 403 Unknown error, whereas the other app(clone) works fine in the other server.

How does navigator.sendBeacon() behave differently even after both the servers are just clones ?