To be fair, the antenna in the A9 is pretty good. Most of the problems in playback is caused by my iPhone 5. But my A9 is also placed close to my router.
BUT the A9 is the only b/g only unit I have on my network, which forces me to have a b/g network active. This means a poorer range and higher risk of interference from neighboring networks.
For an instance, inSSID gives my b/g network a "link rating" of 30 at best. This rating depends on signal strength and other networks on the same channel. My n network on the other hand have a perfect 100 score.
The problem with b/g is not the bandwidth, it's the overpopulated channels which decreases the range and stability of the network.
I love my A9 and after some intense network setup the connection is stable, but not withouts faults. If I had the opportunity to use a n network does stability issues would be non-existing.
The A9 is still a killer product, but the price justifies top notch technology!