Something bad with that pool :/
Sometimes pool hashrate going down from 3.8 MH/s to 1.8MH/s, even my miners go down to the half of my actual hashrate, and it doesn't really matter if I have the keepalived on :/
It doesn't tell much about the problem.
Could you PM me more details about it : When did it start, how often does it happen, what's your configuration (how many GPUs and IPs), is your connection stable, does it happen with other pools ?