Wow, someone else that uses a exactly the same router as I have to!
I've tried EVERY suggestion on this thread, plus another thread on answers.microsoft.com where there's now (1 April 2014) 36 pages and 300+ replies (and that's no April fool's joke) to this "limited connection" wifi problem and none worked.
So thank you thank you thank you for posting this! :D It was driving me insane!
Incidentally, to anyone who thinks using specifically Channel 11 is necessary - it might be an idea to download a wifi scanner / analyser (eg Netgear Genie or WiFi Analyser (on Android smartphones) to have it scan to see which channels are
least in use and choose that. Luckily Channel 11 happened to be completely free of other APs for me.
For info, if it's useful to anyone else, I'm using an Asus N55SL Laptop, Win 8.1, Intel Centrino Wireless-N 1030 wifi adapter (built-in), which had been working on every other OS I've tried (Linux, Win 7 for over a year and Win 8.1 (for a couple of weeks
until it went mental a couple of days ago for no apparent reason)). I have never, in about 20yrs of IT usage and tech support, experienced this type of problem with wifi!
The weirdness was that every other device in our household (iPhone, iPad, Win 7, Apple TV, Android smartphone) had NO issues at all with the AP. Just my Win 8.1 Laptop. But then my laptop was perfectly stable with other wifi APs, which made NO sense whatsoever.
Things I tried included updating wifi adapter drivers, rolling back drivers, reinstalling latest drivers, rebooting router a few times, updating laptop firmware, updating router firmware, resetting the IP stack, enabling the "download over metered connections"
setting, using the almost entirely useless troubleshooters that are built-in on Windows, disabling the power management functions of the wireless adapter, setting it up not use 802.11n, forcing 20Mhz only, roaming aggressiveness to low, high and medium, transmit
power to low, high and medium, and disabling Ad Hoc QoS / WMM, ensuring Windows Power profile was on Max Performance, flushing the DNS cache. Phew!
So yeah. You rock. Thank you!