I've had a similar problem with my UE46ES7000: fine connecting with an ethernet cable, but when I tried to connect wirelessly the TV just scanned for a while and found nothing. I tried updating the firmware but still no joy.
Having looked around the various forums for ideas I eventually contacted Samsung, who said it was probably a NIC (network interface card) issue, and suggested I contact John Lewis, who sold me the TV three years ago, since Samsung offers only a 12-month warranty. The John Lewis customer support guy put me through to the technical support team who, hooray, managed to fix the problem.
For me - and I realise this may not work for everyone - the solution was to do a factory reset of the TV. You do this by turning the set off, then press, in sequence on your remote control, info-menu-mute-on. This brings up a menu on the screen that includes a factory reset option. When you click this the TV turns off, and when you turn it on again it runs through its full set-up sequence. This is different to doing a set-up through the normal menu - I'd tried that previously and it didn't find the wireless routers, whereas this time it did.
I hope this helps at least some of you who have the problem - and for the rest, you have my sympathy because maybe it will be something to do with the NIC.