The database mirroting cannot listen on port 1600because it is in use by another process

Hello,

I have an issue creating SQL 2012 R2 Always On Availability group, i was able to create it for 2 name instance but when i am trying to add availability group for the 3rd instance it give me the below error 

i did not use this port for any other service or instance, also i tried to change the port many times but i still got the same error