Web Console does not start in combination with many network connectors

We have ActiveMQ in use with broker network. We have added recently some new brokers to network and we found out, that web console does not start any more.

We have a "master broker", which has several connections to subordinate machines:

<networkConnectors>
 <networkConnector duplex="true" uri="static:(xxx)" name="xxx" />
 <networkConnector duplex="true" uri="static:(xxx)" name="xxx" />

 . . .

</networkConnectors>

We have currently 13 connectors in place. And the console does not start. When we reduce number of network connectors, then web console starts again.

We have noticed the same behavior with previous version 5.15.13-87. I think, therefore that the problem is not version specific.

There was no relevant error in logs, which I could attach. It seems that simply the start of web console is not executed, when there is too many connectors.