Canon PIXMA iP8750 - Manual (Page 265)

Printing Speed Is Slow
Check1 The printer may be printing out a large job issued from another computer.
Check2 Make sure that the radio status is good and adjust the installation positions
while monitoring the radio status with IJ Network Tool.
Monitoring Wireless Network Status
Make sure that there is no barrier or obstacle between the access point and the printer. Wireless communication
between different rooms or floors is generally poor. The metal, concrete, or timber including the metallic material,
mud wall, or insulator may interrupt a wireless communication. If the printer cannot communicate with the
computer over a wireless LAN for the wall material, place the printer and the computer in the same room or floor.
Check3 Make sure that there is no source of interference in your vicinity.
If a device (e.g. microwave oven) using the same frequency bandwidth as the wireless station is placed nearby,
the device may cause interference. Place the wireless station as far away from the interference source as
possible.
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