New Z3 wireless issue - bluetooth interference?

This is my third Z in 5 years: I just got a beautiful z131190X, but now I started noticing slow wifi connections in some situations:
- My home network is a 802.11n with both 2.4Ghz and 5Ghz enabled, all of my devices (including my previous Z12) connect flawlessly and speed test and approx 20Mb down, and 5-8Mb up)

- My new Z3 consistently experienced slower speeds and overall network latency. I then decided to play with the wifi bands in the Vaio Smart Network app, and found that if I select 2.4Ghz only, or 2.4Ghz/5Ghz mode, the connection would be slow. If I select 5Ghz I then get great download speeds.

- Also, if I turn off bluetooth, wifi network speeds do improve, especially in the 2.4ghz band.

This never happened to be on any of my PCs.

Any ideas on how to keep 2.4Ghz and bluetooth on and still keep a great connection?

 

As far as I remember, 802.11 b g n operate in 2.4GHz frequency band;
Bluetooth also operates in 2.4GHz frequency, it is quite common to have interferences if you enable both mode.

Fortunately 802.11a and n has 5GHz mode, in that case you can avoid the performace drop.