3Com BR-6574N manual Here. If you don’t know which one you should

WEP

Select WEP to enable WEP (Wired Equivalent Privacy) encryption:

Here are descriptions of every setup items:

Item Name	Description
Key Length	There are two types of WEP key length: 64-bit
	and 128-bit. Using ‘128-bit’ is safer
	than ’64-bit’, but will reduce some data
	transfer performance.
Key Format	There are two types of key format: ASCII and
	Hex. When you select a key format, the number
	of characters of key will be displayed. For
	example, if you select ’64-bit’ as key length,
	and ‘Hex’ as key format, you’ll see the message
	at the right of ‘Key Format’ is ‘Hex (10
	characters), which means the length of WEP
	key is 10 characters.
Default Tx Key	You can set up to four sets of WEP key, and you
	can decide which key is being used by default
	here. If you don’t know which one you should
	use, select ‘Key 1’.
Encryption Key 1 to 4	Input WEP key characters here, the number of
	characters must be the same as the number