Am I doing this right?

[Gabis1207]

Tried that some while ago. those adapters didn't work very well, since our house has (very) old wiring, and we have 12-16 cellphone/laptop chargers going at any given time. According to this site, older wiring, chargers, and other things plugged in cause interferance.

 

[PP Mguire]

Well I could see how it would work if they allowed multiple MACs from one service address. Simply using the same connection going to each modem could do this. Using extra devices like you linked above could cause signal issues though.