The most likely techie explanation (IMHO) would be a race issue.
A race hazard is when there are two parallel conduits (wire/logic or in this case packets), then there is the handshaking - acknowledge-received & send more kind of thing.

Maybe the wireless is slowing up the transfers and the handshaking has been done before more packets start to arrive. I am not sure but maybe wireless is one way at a time, and cable allows both directions simultaneously. Which could cause a race hazard. Plus a unique condition with your location/set-up.
Just like steering your car is easier at lower speeds because the delay in your brain (250 mS ish) better suits the speed of information arriving to it.