I have been trying to find a solution to a specific problem. Let me explain before I ask my question
I travel around Australia in a caravan that wherever possible uses 12vdc (important).
I have now purchased Starlink
There are VAST amounts of Australia that do not have easy access to Internet (thanks to Elon that's now solved), but there are still large numbers of people who cannot afford the setup. On top of that our 3/4/5G coverage only covers about 20% of the physical country (around 90% of the population - as we are VERY urbanised). That leaves those away from the urban centres in a bind.
I travel around and stay in free camps (boondocking) wherever I can. These tend to be more remote places. Lots of people in those areas would happily pay for access to a basic Internet connection. My plan is to sell 'excess' bandwidth from my starlink connection
OK enough about the background. What I need is a recommendation for a modem that:
I can power using 12vdc (or 5v USBC type)
I can use with OpenWRT
I can install OpenNDS (and this appears to be the killer).
The reason OpenNDS is important is I don't want to need another computer as a radius server (for example). It takes additional power and adds additional complexity.
I have a Gl.net AXT1800 slate which I thought was going to be perfect, BUT... I cannot get OpenNDS to install. Lots of attempts and all failures.
I commented on your other post about the ATX1800 and it probably works.
However this router does not yet have official OpenWrt support (but it looks like it is well on the way).
More important is your 12v requirement.
I understand this entirely for your application. Do you have an effectively unlimited 12v supply? ie big battery bank and lots of solar panels with lots of sunshine?
If so the best way to power a router is to use a small pure sine inverter to give you 230V 50Hz.
The AXT1800 and similar routers often have a usbc power input, but require a 3A peak supply. Many car type adaptors are only 2A so can be a problem.
If you have the 12v capacity to run an inverter all day, then I would suggest the Gl-iNet MT1300 (Beryl) as it is already fully supported by OpenWrt.
If power is a precious resource then for openNDS, running it all on a Gl-MT300-V2 will give excellent performance for sharing your Starlink all from a plain old 1.5A usb car adaptor.
There is the high probability that the supply is only nominally 12v. A battery bank supply can be as high as 15v and as low as 11v so some regulation will be required. Just an off grid problem to solve one way or another. General purpose DC to DC voltage converters are cheap and a good way forward too.
Most routers that I have had a look at have an internal regulation circuit anyway - the CPU runs on 3.3V or 5V, USB is 5V ... so that question is: how good is it and what are its limits?
Car electrical system is, as someone said, only nominally 12V. Actually, 12V is when running only on very empty battery. While charging, it is around 14V, but the most dangerous things are spikes that ARE happening. As far as I remember, these spikes are typically clamped to 40V which is the voltage every car-rated electronic component must withstand for a few (hundred?) miliseconds. These spikes are probably going to kill the router's input power regulator.
Yes that is true about internal regulation, and of course it all depends on the design. But running nearly 15 volts when 12 is expected could well result in dangerous overheating. Likewise running 11 volts or less may well result in under-powering. Not many devices are specifically designed for off grid use with wide tolerances in DC input voltage, so a degree of care is required.
