Slow and then non responsive mqtt.read

Hi 

I am using an ESP 32 with the the example. I am experiencing strange behavor. 

A published message its taking a long time to arrive. Then I can send a message and it does not arrive. Operation is not consitant. 

Is there any debug to see why. The message then might arrive a later.

Tried different QOS / Retain true / flase and the issues alwasy occour.

Help. Its just not usable.