MacBook Air loses connection to internet but not LAN

Question

Hi, I am using a MacBook Air 11" (mid-2012) running OS X Mavericks (10.9.3). I'm connecting to my home LAN via WiFi connection to a TP-Link 300M Wireless router that is setup as a switch (per instructions here http://www.tp-link.com/en/article/?faqid=417), which in turn is connected via wire (ethernet-over-power) to a Technicolor cable modem/router provided by my ISP (UPC in the Netherlands; I can look up the model number of the router if needed, but it's two floors down right now and doesn't strike me that this is the cause of the problem).
I have a problem that my MacBook Air intermittently loses connectivity to the internet for extended periods (minutes) even though (a) the MacBook Air maintains full connectivity to my LAN at the same time through WiFi and (b) other computers connected to the cable modem/router maintain their connection to the internet while my MacBook Air has lost its connection.
My test to see where the breakdown is occurring is to have four terminal windows up and running ping processes:
1) ping to 192.168.0.1 (my router) - this always stays live, with essentially no lost packets
2) ping to an external address (I'm using 74.125.136.94, a google.nl address) - this is my main test for access to the internet and where I see ping failures (I'm also testing with pings to other sites when the problem is occurring to ensure it's not something on the remote end).
3) ping to 192.168.0.13, which is a Synology NAS attached via ethernet cable to my main cable modem/router - this always stays live, with essentially no lost packets.
4) a login to the Synology NAS, where I am also running a continual ping to 74.125.136.94, and this external ping does NOT fail when the one from my MacBook Air does, it stays live with essentially no lost packets.
The problem will usually correct itself after 1-3 minutes (though the time is not consistent), and also gets corrected if I turn the MacBook Air's WiFi off and on again.
Any suggestions for what I can do to stop this problem?
Thanks
John

Answer 1

> 1. If the MBA is connected to the
>     a. the Technicolor SSIDs, is the behavior the same (poziom-k testing shows that a second AP causes problems).
No. If connected to WiFI served by Technicolor, the problem does not occur (even if the other AP is connected to the network).
>     b. can the Technicolor be replaced easily by an Airport Express/Extreme, to repeat this test?
Unfortunately, Technicolor in router mode is required by my ISP.
> 2. Instead of WiFi, if the MBA is cabled to the secondary AP, is the behavior the same?
Yes.
> 3. Has Wireless RF interference been ruled out for dropped connections?
Yes. A Windows machine and several iOS mobile devices work flawlesly for me.
> 4. If the MBA has a wired connection to the Technicolor, does the problem still exist?
No. The problem occurs only if connected through additional AP.
> 5. Have packets been captured at each interesting point in the topology to see where are packets drops occurring? netstat -s is probably worth looking at > such points. Wireshark (or similar tools) can help.
Not yet. I will not have a chance to do it for the next few days though :/