I have installed OpenWRT on my Linksys WRT1900AC. The latest version that I see published for it and I have installed is 18.06.5.
Now I want to use nextDNS. I see that it has been implemented for version 19.07: https://github.com/openwrt/luci/pull/3291
OpenWrt 19.07 is currently at RC2, so I expect it should be released "soon".
The 19.07 RC image for WRT1900AC can be found here https://downloads.openwrt.org/releases/19.07.0-rc2/targets/mvebu/cortexa9/. RC2 sohould be reasonably stable, however, it's not the final release yet, so if this is your only router and you like to minimize any risk of hiccups, you could search the forum to see how this version is doing on your router model.
I don't specifically want it on 18.06, but it is the most recent version that I found for Linksys 1900ac and I don't have enough expertise to know if I can install the 19.07.
Thanks @Hegabo and @neheb , I have upgraded to 19.07 with the link provided by mhegab, installed NextDNS and OpenVPN and both are working fine in my Linksys 1900ac.
Following some begginer steps in case it is of help to some novice like me:
Connect to the router with your WebBrowser (http://192.168.1.1) and in Luci interface:
system\backup\FlashFirmware\Flash new firmware image
load the .bin file that you just downloaded to your computer.
Goto System\Software and UpdateList to refresh the available packages names.
Filter: nextDNS
Install: luci-app-nextdns
And the new menu appears in your router Luci \Services\NextDNS
where you must introduce your NextDNS configuration ID
Filter: Openvpn
Install: luci-app-openvpn
And the new menu appears in your router Luci \VPN\OpenVPN
And now you can do all the configuration of the OVPN with SSH
Note that it is now also possible to install nextdns on previous versions of OpenWRT thru our installer script. You won’t have UI and it won’t be a package tho.
@Hegabo I would... if I knew how to... there is no longer the pencil in the bottom of the first post and the on in the upper right doesn't allow me to edit it...