Connecting a bluetooth headset while connected to WLAN disconnects both WLAN and bluetooth

This could use a little more detail. Are we talking about scanning for bluetooth devices or connecting to an already paired one? Do you initiate connecting from the phone or the headset? Details about the headset and the wlan might also be helpful.

I do this on a regular basis, connect my bt headset when connected to my home or office WLAN, and so far I haven't seen this issue.

Add the type of BT headset, is the Bt headset already paired? Is it with all the WLAN's and BT headsets?

Thank you very much for wanting to help me! I have 3 bluetooth devices and all have problems. All of them are paired (have in the phone memory) with the phone. There are problems: 1) Talking on the phone (I have always included WiFi connection) and try to connect jabra jx10 (or Nokia 905i or Nokia BH-214) - just be lost and WiFi connection until I disable Bluetooth - WiFi does not connect ... 2) It often happens that I was talking on the phone and want to switch it to Bluetooth - turn it on the phone and connect the headset talking ... but in addition to the voice in your ear appears ringtone (nokia tune) - as if the incoming call is .. tried to change device , cut off one another and are connected - all the same .., voice and melody .. Please excuse me for my bad English.

From your description it sounds like you're always in an active phone call when this happens, is this correct? Do you lose wifi if you connect a bluetooth headset when you're not on a call.? Could it be that it always disconnect wifi when you're on a call, but you don't see it unless you use a headset since you'd be holding the phone to your ear?