Oops , looks like I have . 
Historically on my Second Modem, as already moaned and got another one sent .
And as usually exactly the same., terrible
So unless we have 5 phones 3 laptops a Sky Box and now a Smart Tv all with reception problems ,the common denominator will be the Router. 
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Wifi reception is amazingly poor , I thought Our old Plusnet supplied router was a bit duff but this Talktalk one out duffs it by a fair margin.
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Stand in the same room ( within a few feet)and resonable, but wander anywhere else in the home and getting a signal is potluck.
From all the other messages about this sort of thing, points to it being firmly inTT's court to sort out ! .
My layout doesn't lend itself to a LAN setup without drilling lots of holes in walls, so not going that way until its a last resort. and really relucctant to splash out cash on an alternative router, esp as TT will wash their hands of any support .
Mini whinge over.. any clues peeps.
Has anyone fitted any external Antennae on thier 633 to help the ailing wifi ?
ta
Chris