Brother MFC 5840CN - Manual (Page 31)

3 - 10 FRONT PANEL SETUP
NC9100h_FM6.0
Setup Misc.
Ethernet
Ethernet link mode. Auto allows the print server to operate in
100BaseTX full or half duplex, or in 10BaseT full or half duplex mode
by auto negotiation.
100BaseTX Full Duplex (100B-FD) or Half Duplex (100B-HD) and
10BaseT Full Duplex (10B-FD) or Half Duplex (10B-HD) fix the print
server link mode. This change is valid after the print server has been
reset (default is Auto).
1 Press Menu/Set , 5 , 2 , 1 . ( 4 , 2 , 1 for MFC-5440CN)
2 Press ▲ or ▼ to select Auto/100B-FD/100B-HD/
10B-FD/10B-HD .
3 Press Menu/Set .
4 Press Stop/Exit .
If you incorrectly set this value, you may not be able to
communicate with your print server.