@Ced2ric 

Got an idea..

Had this strange scenario once where the printer (HP) would always connect to the furthest away AP..   turns out the WiFi card in the printer scanned for the SSID in acending order of channel (1-11).  Therefore it seen the SSID on channel 1 and connected each time, even though the AP was the furthest away.

Check the AP its connected to and see what channel its on, notice your post above the AP 650 is on channel 6.. hopefully the other AP is on 1 to 5 and that is your issue too.

If so, swop the channels to have the 650 on channel 1, other AP on 6 and retry

Hopefully that is your issue!!!