If you don’t want to use the O2 Broadband provided router and would prefer to use your own Linksys WAG354G, here are the configuration settings you require (note: this assumes that you have a static IP address):

Encapsulation: RFC 1483 Bridged
Multiplexing: LLC
QoS Type: UBR
Autodetect: Disable
VPI: 0
VCI: 101
DSL Modulation: ADSL2+

Internet IP Address: supplied to you by O2
Subnet Mask: 255.255.252.0
Gateway: supplied to you by O2
Primary DNS: 87.194.0.66
Second DNS: 87.194.0.67

PPPoE Session: Disable

MTU: Manual
Size: 1500