I have an issue where the MonoDevelop debugger refuses to connect to the simulator. MonoDevelop pops a box saying \"Waiting for debugger to connect on 127.0.0.1:10000...\" b
I was having the same problem and I'll share my solution in case anyone else made the same embarrassing mistake. I didn't have wifi enabled, so my iPhone didn't have a NAT address like 192.168.1.xxx, so it wasn't able to contact the NAT address that MonoDevelop was listening from.
Enabling wifi and connecting to my home network fixed it.