The issue of two people being able to connect to each other and when a third person joins, everything goes black

Hi Team ,

I am having the issue of two people being able to connect to each other and when a third person joins, everything goes black.

We have installed Jitsi server on Ubuntu server 18.04 version .Ubuntu server have two IP address (one local ip address & one nated public IP )
please find the jvb log files.
tail /var/log/jitsi/jvb.log
at org.jitsi.utils.concurrent.RecurringRunnableExecutor$1.run(RecurringRunnableExecutor.java:328)
2020-06-19 09:27:11.995 INFO: [18] VideobridgeExpireThread.expire#144: Running expire()
2020-06-19 09:27:12.254 SEVERE: [20] AbstractHealthCheckService.run#174: Health check failed in PT0S:
java.lang.Exception: Failed to bind single-port
at org.jitsi.videobridge.health.Health.performCheck(Health.java:192)
at org.jitsi.health.AbstractHealthCheckService.run(AbstractHealthCheckService.kt:144)
at org.jitsi.utils.concurrent.RecurringRunnableExecutor.run(RecurringRunnableExecutor.java:216)
at org.jitsi.utils.concurrent.RecurringRunnableExecutor.runInThread(RecurringRunnableExecutor.java:292)
at org.jitsi.utils.concurrent.RecurringRunnableExecutor.access$000(RecurringRunnableExecutor.java:36)
at org.jitsi.utils.concurrent.RecurringRunnableExecutor$1.run(RecurringRunnableExecutor.java:328)