Making an actual telnet connection=garbled text

[captain_zzap]

Hi,
I received my WiModem today, which is nice. 
I've set up the wifi and can sucessfully connect to bbses. But when I'm connecting to my local server(an arch-linux machine) through telnet I don't get a login prompt, but just a few garbled characters. Same situation when I connect to my Mac.
I tried changing the terminal type(ANSI, Commodore, VT102) which didn't change anything.
When I launch telnetd with an invalid option and try to connect, I get an error message on my c64 which doesn't get garbled.
Has anyone used a telnet connection and knows how to fix this?

Thanks