I mine on zPool and noticed that a couple of my Z9 Mini's were missing from the pool. When I checked the miners, they were stuck mining on the dev pool and had been doing that for over 12 hours and not flicked back! How do I stop this from happening again? This is way more than the stated 1%.
Hmmm 1%

? not even close - I use awesome miner to run my miners and what its reports show me that zec-bj.poolin.com (I do not mine on that pool so I assume that is a dev fee pool) in the last 7 days was mined on 5.98% and 6.7% in last 24 hours.
I will provide more details on it later. There is something really strange that is going on with 2.1c. I am not 100% sure if that has to do with new awesome miner update or 2.1c I have dedicated 5 minis and 5 bigies to run some tests and get to the bottom of it and will provide mining history reports shortly. But so far I definitely noticed increased traffic to poolin.com on the firewall; Slush poll mining became really unpredictable - meaning some miners will be reported on the pool side some will not even though awesome miner and miners web gui will show them mining with 0 rejects on Slush. (may be it is what spoonwzd described- I will check on this) Also miners started to get disconnected more often due to socket error and even though they haven't been rebooted when they re-connecte they will start dev cycle again... On the side note: Sorry Jason, I am not trying to bash your work and definitely not trying to accuse you in being dishonest about 1%. For all I know it might be just my set up and I apologies in advance if it is - I will post an update with reports shortly
I had a similar issue and notified Jason a few weeks ago. The miner was connecting to his callback server and dev server more then it should. I was using the netstat on the machine to monitor its connections.