FLYPROFiber- 30M OS2 Fiber Patch Cable LC to LC, Length Options: 0.2m-200m, 1G/10GB Single Mode Duplex, 9/125um SMF Fiber Optic Cable Cord LSZH 30Meter(98ft)

you could install additional ethernet wall jacks. branch off from the port upstairs with a switch there. and plug everything in to said switch. another option would be to get a couple of media convertors and some fiber, run said fiber around baseboards and over door jams and glue it. it will be nearly invisible. 2 x https://www.amazon.com/TP-Link-Ethernet-Converter-Supporting-MC220L/dp/B003CFATL0 2 x https://www.amazon.com/TP-Link-1000Base-LX-Single-Mode-Interface-Distance/dp/B003CFATYW/136-6065964-6270207 example of fiber https://www.amazon.com/FLYPROFiber-Fiber-Patch-Length-Options/dp/B08BZBS5FT/136-6065964-6270207 extra fiber can be coiled up on the ends. you can put a switch where the first media convertors plugs into the upstairs wall ethnernet jack and also at the end of the fiber where the second media convertors is.