This is untrue, disconnects happens mainly due to routing issues or maybe, just direct-attacks in your servers or even servers in the same rack, taking ddos attacks, causing problem to your server since both shares the same switch.
However, you should work with them any issues you have, and if the issue is not fixed, you need to let them know about it, until you both, find the solution :).
Dedicated Servers with included DDoS Protection, doesn't works, at least I didn't saw any with good stability, OVH, Voxility and for example BlackLotus are pure examples of how this doesn't works the way it is expected.
Your solution is not bad, but if it need adjustments, just make sure to be speaking/insisting with your company, because it is currently one of the best out there...