Newifi Mini has reliable hardware(MediaTek MT7620A 580MHz, 16MB Flash, 128MB RAM, 2.4G/5G WIFI, 1 USB 2.0 port) for flashing third party firmware, but the features of official firmware is very limited, and you have to flash the firmware in order to install other software.
I tried both OpenWrt and PandoraBox, and PandoraBox's WIFI signal is much better than OpenWrt. OpenWrt works fine except the WIFI signal. So I decided to use PandoraBox, and it worked well for months without rebooting.
3.Disconnect any WIFI, and connect your computer to the router with cable.
4.Install xRouterManager and run.
Enter your router password(default password is admin) to unlock, click "Advanced recovery", and choose the firmware in step 2, click next and wait for flashing complete.
Configure the router
1.Enter http://192.168.1.1/ in the browser, username "root", password "admin".
2.Select System -> Software -> Configuration tab, and replace the text with the code below:
arch all 100 arch ramips_24kec 200 arch ralink 300 arch ramips 400` dest root / dest ram /tmp lists_dir ext /var/opkg-lists option overlay_root /overlay src/gz r2_base http://pb.scorpwill.com/base src/gz r2_management http://pb.scorpwill.com/management src/gz r2_packages http://pb.scorpwill.com/packages src/gz r2_routing http://pb.scorpwill.com/routing src/gz r2_telephony http://pb.scorpwill.com/telephony
Install applications and configure
1.Run cmd, and telnet to the router.
Enter password "admin"
Remove old packages
opkg remove luci-app-chinadns opkg remove ChinaDNS
Install wget and ca-certificates
opkg update opkg install wget opkg install ca-certificates
2.Install additional packages
Add package source in System -> Software -> Configuration
src/gz openwrt_dist https://mirror.scorpwill.com/openwrt/base/ramips src/gz openwrt_dist_luci https://mirror.scorpwill.com/openwrt/luci
Install ChinaDNS and shadowsocks
opkg update opkg install iptables-mod-tproxy ip ipset opkg install ChinaDNS opkg install luci-app-chinadns opkg install shadowsocks-libev opkg install luci-app-shadowsocks
Select Services -> shadowsocks in your browser.
Add a server, enable Transparent Proxy and Port Transfer(port: 5300, DNS server: 220.127.116.11:53).
Enable ChinaDNS in the menu, and change upstream DNS server to: 18.104.22.168,127.0.0.1:5300
4.Select Network -> DHCP and DNS
Change DNS forwardings to ChinaDNS address(127.0.0.1#5353)
Select Resolv and Hosts Files tab, check "Ignore resolve file" and "Ignore Hosts files"
Replace "conf-dir=/tmp/etc/dnsmasq.d" to "conf-dir=/etc/dnsmasq.d"
mkdir /etc/dnsmasq.d && cd /etc/dnsmasq.d
wget http://mirror.scorpwill.com/dnsmasq.d/bogus-nxdomain.china.conf wget http://mirror.scorpwill.com/dnsmasq.d/adblock.conf
Congratulations, you have successfully installed PandoraBox, and your network is totally free now.