1.7km is quite long for WiFi but it is not unheard of.

My suggestion is to use Satellite dishes for both houses. Use a TP-Link AP-client setup (something like a TL-WR741ND) and make a homebrew biquad antenna connected to a short coax cable that goes to the TP-Link.

Make sure the TP-Link is installed inside a sturdy outdoor housing of some sort. Then connect the TP link AP to your ROuter's LAN port and the TP-Link client either directly to PC or to the other house WAN port.

Also stick to 802.11g. For long range wifi MIMO is tricky and could worsen performance. Its unlikely you can get anything better than 6-8Mbps anyway.