I have a Linksys WRT1200ac router that I have flashed Dec 29 2017 DD-WRT firmware on.

I believe you can connect via ethernet to it and configure it using Windows. At the moment I don't have a Windows machine or legal software.

I would like to be able to have a totally wired network with VPN. I got the VPN working ok, but if I disable wireless on the router I can't connect to it at all. At the moment I can connect via a Android Samsung Tab A and configure it that way wirelessly.

I'd like to be able to access my ISP's modem and my router via ethernet and only have ethernet enabled on them.

How can this be done in linux?

DD-WRT uses a web server for its setup configuration as well as running a ssh server so it should be accessible via a wired connection regardless of operating system. Depends on DD-WRT version and capability of your router but you might of configured a wired port as a separate network. The default IP/network is usually 192.168.1.1/24.

A usb to ethernet dongle does wonders. I setup my dd-wrt asus rt-n12 with a pocketchip with an ethernet dongle.

$ firefox http://192.168.1.1

Plus the usual dhcp stuff for the ethernet.

# dhclient -4 -v eth0

DD-WRT can act be set in a few modes. As above you use a browser. Maybe new default IP.

One mode will be common soho router. If on different subnet then you can easily access wan modem. Example. Lan subnet 192.168.0.1/24 and modem 192.168.1.1/24 will easily connect though to modem. I'd think this is a common way to run dd-wrt. There are other modes that will work also.

DD-WRT is very useful if you take the time to learn how it can be used over the stock firmware. Otherwise you have made no improvement. I'd see about FWbuilder to make a good firewall in the router.

Thank you everyone for your quick replies.

As this was my first attempt done using Linksys program on Android Samsung tablet it most likely does have errors in configuration. How-to's show Windows only. Chrome doesn't work when used as an ethernet connection. The quick setup guide uses a wireless connection, with a not easily guessable password.

It was hacked I suspect using wireless network, though I thought I had disabled wireless after setup. The ISP modem does not appear to have been hacked. Hence I suspect it was hacked wirelessly.

I will try out some of the things suggested which may take me a while, reconfigure / find backup for router and get back if I still have issues.

So once again thank you all for your help.