Most of you know better, but let's try to be helpful
Look at the kernel log / connect whattomine / look at your mining stats and you will all see how it works:

every two hours it will mine exactly 1 minute and 50 seconds on one of the dev pools I hardcoded. This goes automatically / independent of the pools you have configured yourself. After that it will mine 2 hours on your pools again etc....

If you do see a reduced hashrate on your pool I think this might help some of you:

• you're on an older firmware  which had a bug where it could not switch back to the main pool if it was down and it could hang for two hours in the dev pool.
• you only have one pool configured. If your main pool dies it will jump to the next alive pool (which is then the devfee pool)
• your main pool is not stable so it switches to the backup pool sometimes (which will cause that the hashrate is divided over two pools)
• you mine on a pool that scams you
• you have so many hardware errors / xxxx that kills your hashrate. (and have auto reboot disabled)
• you have an unstable internet connection: this will cause that you get the work packages late and you get a lot more then normal discarded shares, because they couldn't be delivered to the pool in time
• Same as the previous point, but then a bad connection on the pool operator side.
• For some other reason your d3 just doesn't like my firmware -> just flash back to stock ( I can't think of anything else then the above, but I am just a human...)

Ok so where to start: the kernel log will be really helpful if you experience problems. Furthermore you can run a ping on the pool for a few hours to see if you get lost packages. If you're still in doubt: just post your problem here (describe it good and post your kernel log) so myself or a fellow forum member can help you out.

edit: added the last line, which is a possibility of course :')