PC is wired and laptop is wireless,as is daughter's laptop and none of them have every experienced problems with downloading any updates or SPs.
It could happen but it is more than likely that the computer will just carry on downloading if there was any wireless interruption.
If a download became corrupted for that reason (or any other) it would not install and you would get an error message. You just download a fresh version.
Ask yourself how often your web browsing or whatever is interrupted by wireless fluctuations? Not very often, the same goes for downloading updates or software.
For the hassle of bringing the laptops to where the router is 'half hidden', plugging in the ethernet cable and running it to the router, it is not worth it.