Kudos to the devs who ported OpenWrt to DIR-505, however the default image is not very easy to use/configure post-flash as the wifi is off by default and the only ethernet port is configured as LAN. Also, stock image does utilize the mode switch slider of this excellent router.
Hence I've built an OpenWrt 15.05.1 and LEDE 17.01.0 images with:
1. Proper Router, Repeater and Hotspot configurations pre-set for the slider switch (thanks to @manishgkasera's script). The only ethernet port acts as WAN port in Router mode.
2. Uses Dirk's travelmate for LEDE builds (only active in the Wireless Repeater mode) and home-cooked STA disable script in OpenWrt build.
3. WPS button acts as reboot, so if you need to switch mode -- use the slider and then press/release WPS button.
4. Lightweight adblock in Router mode.
5. Auto-generated WiFi SSID and password in the form of OpenWrt-XXXXXXXX where Xes are random 8 hex symbols or LEDE-XXXXXX where Xes are the last 6 symbols of eth0 MAC address. Same SSID and password (case-sensitive). Not very secure, but better than static SSID/password.
6. No default root password set -- immediately connect to your DIR-505 after flashing and change it.
7. Luci and miniupnpd; full wpad and dnsmasq -- just because.
8. LAN IP is 192.168.0.1 in Router mode.
9. Material theme for Luci, because it looks so much better on smaller screens.
Both OpenWrt and LEDE images can be downloaded from: https://github.com/stangri/openwrt-images
Please verify md5 hash before flashing and flash images at your own risk -- I got rid of DIR-505v1 and have no way to test those builds anymore.
(Last edited by stangri on 1 Apr 2017, 05:11)