RFXtrx and zwave on Synology

I am running HA on a raspberry and have directly connected Z-Wave and RFXtrx via USB. Now, I installed HA on my Synology in docker and need to find a way how to connect the two networks Zwave and RFXtrx. The problem is that the NAS is located in the cellar and the two USB ports are already occupied.
Are there any solutions to that? I thought of a kind of USB server hub but could not find anything suitable,

Perhaps you can try a powered USB hub. This works for me.