Thanks very much for the info. I ran a video file from the sd card: no lockups.
I changed the channel to a channel that wasn’t used by other access points around. The signal is strong. It did not resolve the issue.
Now I did some experimenting and I am not sure yet (need more testing) but it seems that the wii has a bad wifi reception when it’s under the tv. I moved the wii away from the tv and no lockups so far.
Does this make sense? If it does, that’s too bad, I had the wii sitting on a shelf with the tv on a movable table…