Hmm, I just looked at the manual for the LB1120. It looks like it has two modes: router and bridge. Did you by chance flip it to bridge mode? While in router mode I see no reason why you shouldn’t be able to plug your WCO base into it and have everything working.
Take a look at the PDF manual linked below. The bottom of page 16 talks about plugging in a switch and using the device with multiple computers/devices. The NetGear must be in router mode in order for that to function. Then on page 23 the manual walks you through how to change the device from router to bridge or visa versa.
NetGear LB112x user manual PDF
I would start by ensuring your NetGear device is in router mode.