If the interfaces your box don't support more than 100 Mbit, the only option is what mmpp suggested. Or a USB Wireless AC adapter.
I'm fortunate to have Wireless AC in my box, however the box can handle only up to 120 Mbit bitrate streams, so even only 100 Mbit should be adequate.
It´s a S905X box(only 100Mbit)
Maybe I will test with 300MBit USB Wireless stick from my HiFiberry Raspberry, got only little hope
USB Gigabit adaper ist available at amazon store, will try ASIX AX88178 and Realtek RTL8153