Just be aware that when you enable that telnet access, it is available to both the LAN side and the WAN side of the router. At least one Netgear router I used did that. That means the bad boys can have fun with your system, should they stumble across it.
I like to run my internet connection in “stealth” mode as much as possible. Just the fact you have an open port on the WAN side will invite all kinds of abuse.