Slush support guy says that they are not aware of any issues on their end:
Hello,
unfortunately we don't have any US server issues reported. I can see in our database that your hash rate drops last only for a short period of time and your scoring hash rate is stable , therefore it has no effect on your rewards (thanks to our moving-average based reward system).
However, there might be some internet connection issues which cause these problems. There are not many similar issues from our customers, however, they show from time to time and usually it is caused by worse internet connection or some error in the miner.
You can lower your alert limit to avoid these notifications or you can also try co connect the problematic miners to another server to see if there is any change.
I guess I'll have to try using their main stratum.slushpool.com address and see if the same thing happens.
I'm seeing the same behavior with my miners at a data center on the west coast. It's very annoying. Woke up to a ton of alert emails this morning.
The URL I'm using is: stratum+tcp://us-east.stratum.slushpool.com:3333
Obviously this is affecting a number of us. Either they're wrong and there is a problem on their end, or maybe some sort of general routing problem between us and them.