I've not had any issues previously, but for the last 20 hours or so I'm having a hard time connecting to the pool from my CGminers running my antminer U1's. It's causing me to loose about 10 Gh/s. My proxy miners are fine, my S1's are fine, My RPi setup is fine running BFGminer.
If this happens again, just check that your miners aren't leaking shares to your backup pool(s). This happens to me sometimes, my miners loose connection to Eligius and it shows up as dead for a while and the stats show a drop off. The 'missing hashrate' is directed to my backup pool though. The last time this happened was almost 15hrs ago, but it's been stable since.