I'm running OpenWRT 23, but like I say the Telnet server is a static binary I compiled myself so the openWRT version isn't that relevent. My router was always too "tiny" to install the web interface, but I could use SSH. However Telnet avoids the inevitable problem of SSH clients updating one day and suddenly not wanting to connect to it anymore. I also have FTP installed for file transfer. I built a custom installation image to flash onto it with those and other customisations.