Fiber to Coax or Lan(RJ45) to coax Conversion

I have a Bell whole home modem that is fiber in to my home but the output of this modem/router from bell is only lan (RJ45/Cat5/6) out. Problem is my house does not have any lan cables in the walls. I only have coax cables running behind the walls to the various rooms upstairs.
What I am trying to research is if there is any solutions to convert a fiber(toslink) to a coax and then back to fiber upstairs to allow me to move my bell modem/router upstairs where I have several devices (pc, xbox/ps4, ip phone...etc...) that I can connect directly to the router as I am currently only using the wifi capabilities of the Bell modem/router today. The Bell modem/router is a HH3000 (newest modem for bell that only have fiber in). The other reason I would like to move the modem/router up one flight of stairs is that it is in the centre of my house and would also improve my wireless coverage without having to use wireless range extenders.
If there is no solutions for this or too expensive, then my other option is to see if I can get a Lan (RJ45/Cat5/6) to coax converter and then back to lan so I can at least put a lan hub upstairs so I can then connect all my devices mentioned above to the hub so they are hardwired rather than wireless.
Any thoughts?