You didn't tell your connection type(802.11b or 802.11g or 802.11n)but it speeds- down even if there is one wall so the wireless technologies didn't reach to cable technologies (cable is nearly 1GB per second).But it wont probably affect your internet connection (just in file transfer it would be slower) because an medium internet connection speed is 256 kbps(kilobytes per second)it is not even 1/1024 so, just in file transfer it would be slower.
I have been experiencing slow connection on my WiFi network. There are 2 AP's (accesspoint) 1 is connected to the router upstairs, and the other is stand alone downstairs. Both the AP's are in WDS mode (bridged). I noticed when they are in WDS mode, the connection speed at the downstairs AP, slow down alot. But the connection to the AP upstairs is quite fast.
Modem --> AP 1 (WDS mode) ~~~~ (WIFI) ~~~~ AP 2 (WDS mode) ~~~~ Notebook
The AP1 (upstairs) is set as the master AP, & AP2 is the slave AP.
So why is the connection slow??? the signal strenght of both AP's is execellent.