First of all, the fact that you haven't been connected for 18 hours won't be an issue. Different hardware will interpret your line differently but you've lost nearly 1 Meg in sync speed which is quite a lot.
Can you obtain the full line stats from the new router, i.e. downstream/upstream attentuaion and ds/us noise margin?
Were your problems last night definitely to do ith the old router and not your line?