Welcome to the community
I'm sorry that you're having intermittent speed issues, I know just how irritating this can be.
I've checked your connection and I don't see anything wrong at the moment, but as you said this only happens occasionally, it's not likely I'll pick up on it today.
I think it would be best for you to PM me when you're having the issues so I can test the connection in real time, or at least over a 24 / 48 hour time period.
Catch up with you soon,
Tech fan? Have you read our Digital life blog yet? Check it out