Dataone broadband Modem connected to wireless router- speed appears less?

Hi,I have BSNL broadband connection shared through a Belkin "G" Wireless router connected from Broadband Modem. PPPOE Dialer is configured in the router while broadband modem is in plain bridge mode. Speed appears to be slightly lesser than when I used bridge mode in modem directly connected to Desktop. This Router comes with a factory Default MTU value of 1454. I did some ping tests and this value appears good enough. but, 1492 is the common value for pppoe broadband.Broadband Speedtests shows speed appears around 1-1.4mbps only while earlier I think speeds are much more?TIA+