Never had a single issue with it - I think the online experience is fantastic for a first effort. Have you actually speed tested your Wii? You say your on a stable 4Mb, but do you know what the Wii is achieving down and up?
The speedtester below will work fine in the Opera browser on Wii. Over wireless my Wii averages 1525kb/s down and 630kb/s up, ping is around 44ms.