Use HomePlug AV ("200Mb/s") powerline-Ethernet adapters to connect your TiVo to your router/gateway/LAN.
Rule of thumb for minimally frustrating home connectivity: Use HomePlug AV, rather than Wi-Fi, whenever you can. In other words, for stationary devices, use HomePlug AV. Use Wi-Fi for mobile devices. The TiVo DVR is decidedly stationary.