Re: Actiontec Router: Replace antenna with a better one? Model #? Brand?

I just upgraded my FIOS speed from 15/5 Mb to 75/35 Mb
As part of this upgrade - received a new Actiontec Router (MI424WR GigE) to replace the older MI424WR router.

The old router had a single larger higher gain antenna - the newer router has two smaller antennas

My new wired speed is amazing consistently 80/40 Mb - well over the promised rates
My new wireless speed is great too - 40/30 Mb but only right next to the router in the den.

The old router had a full signal in my bedroom and living room.  I barely get one-bar now with the new router and the speeds are attrocious - less than 1 Mb most times.

So the "upgrade" has become a serious downgrade in reality - i get fantastic speed in my den - but my familiy is effectively shut out from using FIOS at all.  And my wife is very unhappy.  This must be fixed or I must return the equipment and go back to the old plan.  Please understand - this was a one-for-one swap -  the old router system delivered 10-15 Mb to all adjacent rooms The new router wont - nothing else changed - same location, same PCs, same walls, same wireless equipment.  It must be the new router and its inferior transmission power and/or antennas.

I have searched the net and read that this is a problem for several FIOS customers
I have heard the new router was intentionally hobbled to reduce range and signal pirating - i think that is a rumor
I must say however - this router upgrade is unacceptable
The range was promised to be greater in the advertisements... it is clearly less

I want to try to fix this before going further... and It should be simple.  i just need some guidance.
I dont mind spending extra to get a better antenna to restore the range I had before the "upgrade"
But.. I want some specific advice on what to do - which antenna to buy for example ... it should not be up to loyal customers to be forced to experiment with a dozens of antennas to restore old range and performance.

Please tell me what to do - and I will do it. 
Recommend an antenna or antennas and I will buy them and install them.
Please help me.