I have two ADSL modems, the first one does not have wireless, but is configured and working fine at around 6 - 7 mbps (ADSL) on Orcon in New Zealand.
I bought a Belkin N150 wireless router to replace the first one. I configured it exactly the same as the first one, but a speed test confirms that it is running slower than dial up.
One difference I noticed is that the first modem (a linksys) came from Orcon, and didn't have an ADSL username and password set up. The Belkin modem on the other hand wouldn't let me leave the username and password field blank.
Any ideas? I am a techy guy, so it doesn't appear to be anything obvious with the settings I have missed.