[General Maximus]

your power levels are fine, including the upstream. Unfortunately you are royally screwed now. There is a known fault with shub3 in modem mode where it will disconnect every ~30 mins and you will lose your internet connection. Vm are aware of it but don't seem to be doing anything about it; maybe it is their secret way of passively forcing everyone to use router mode (which works fine). Unfortunately for you there isn't anything you can do about it and ringing them up and moaning will be pointless because you will just be wasting your time. If it causes you too much agro the only thing you can do is drop back down to 200mbits and ask for a new shub2 (they won't reactivate your old one) which you might have to go through retentions for.

I wish the government would pass a law where they can get fined for this kind of thing because it is so frustrating. They are knowingly selling a faulty product.