I just get a flashing cursor in the cmd prompt window and nothing seems to happen.
I got that the first time in command prompt. Re-ran the command and it works fine. Try running it again in a command prompt with administrator privileges.
All of these work for me (I have a directory called Temp in the C drive):
cd \Temp
telnet -f zyxel.log 192.168.2.2
telnet -f .\zyxel.log 192.168.2.2
telnet -f C:\Temp\zyxel.log 192.168.2.2
Change the IP to your router's IP, obviously.
I also tried the suggestion in the post above yours, and a word search shows no sign of `supervisor` whatsoever.
Any other suggestions guys?
The output of dumpmdm on my device has around 8090 lines. The password appears around line 158. It is certain to disappear behind scrollback on most command prompts so logging the output of telnet is your best bet.
If logging simply doesn't work for you, increase the scrollback to around 9999 lines, which is the maximum you can set it to in command prompt. Right click anywhere on the title bar, click on Properties, Layout tab, Screen Buffer Size, Height. Change that to 9999 and apply. Then telnet to your device as normal and run the dumpmdm command.
Another way is to use a client like
PuTTY (you can use SSH or Telnet protocol). Before you connect, click on
Window and set lines of scrollback to 10000 or 20000.