Satellite C55DT network adapter problems

Question

I purchased this Toshiba Satellite C55DT-B5208 laptop for my husband late August this year.  I've had two previous Toshiba laptops before and loved them, that's why I did not hesitate to purchase another Toshiba brand.  I am a very technical person and I work in IT, so I am familiar with networking and computer hardware very well.  We have a pretty robust home network.  I recently upgraded our router to the ASUS AC68u Gigabit router, which also serves as our media server.  All of our devices at home do not have any connection issues since I upgraded our router, so I know that when my husband's new Toshiba laptop keeps on disconnecting, it's is related to its network adapter, which is the Qualcomm Atheros AR956x.  I tried all of the following solutions with no success:
1.  Reinstalled the latest driver
2.  Reset the BIOS
3.  Changed the channel bandwidth of our router from 20MHz to 40MHz (this increased the speed of the adapter to the router from 72 Mbps to 150 Mbps, but the Internet is still extremely slow and websites wouldn't load most of the time.)
4.  Used a WiFi analyzer to check what surrounding frequencies are interferring with the connection, but I found none.
5.  Finally, I reset the computer to its factory settings (this seemed to work only for a few hours. The Internet seemed to run fine then started to do what it did before I did the reset). 
I called the tech support for this since it is still under warranty, and I was told to send it in for repair.  My husband needs a computer because he is now in school, and sending it in means he won't have any computer until he gets it back.  Are there any other solutions I am missing?  I was thinking of purchasing a replacement network card for it, but I am not sure what type of PCIe network card form factor it uses.  I cannot find any information on what type of PCIe card it uses.  Any information will be appreciated.  

Answer 1

I have been having similar issues with this same model, purchased at best buy, for my wife. The wifi will suddenly seem to slow to a crawl, and eventually will not work at all. Though, it states it's connected, and there is a problem with the router connnecting to the internet. I have a standard Verizon issued MI424WR router that came with the services. I tried  returning to factory settings, updatind drivers, BIOS, uninstalled antivirus, tried with different antivirus products, firewall settings, etc. Nothing. It seems that when the laptop is taken away from the router, a mere 25 feet or so, it loses connectivity, but insists it's connected to the router, and the router is the one having trouble, though 2 other machines on the same network (1 wifi, 1 ethernet) are experiencing no issues. Really this is just a bump, hopefully someone out there can figure this out.
Win 8.1
AMD A8-6410 APU with AMD Radeon R5 Graphics 2.0 ghz
6.00 GB RAM
HALP!
Caleb