Lexmark 101 - Manual (Page 85)

What is a key index?
A wireless access point (wireless router) can be configured with as many as four WEP keys. Only one key is used on the
network at a time, however. The keys are numbered, and the number of a key is referred to as its key index. All devices
on the wireless network must be configured to use the same key index when multiple WEP keys are configured on the
wireless access point.
Select the same key index on your printer as you are using on your wireless access point.
Networking
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