Just check if they are compatible with dd-wrt or openwrt and flash it with opensource build.
Much easier than flashing cell phone and the open source version normally has more features also.
Much easier than flashing cell phone and the open source version normally has more features also.
I can imagine that you might have an unprivileged server presenting just the log-in page, then proxying to a privileged server that is started once the administrator is authenticated. But that doesn't get you much more security, and it probably does strain the resources of low-end routers. A small, auditable server may be better than a more complicated system, especially since it is trivial for more paranoid users to disable/uninstall the web server and just use SSH (which nobody seems to mind running as root).