1) Access your router on http://192.168.0.1/snmp.htm

2) Enable SNMP and make your community name 'public'. Click Apply.

3) Type in the address bar: http://192.168.0.1/setup.cgi?todo=debug (it will say “Debug enabled”).

4) Click Start, Run, type in 'cmd' to get a command prompt.

5) Type 'telnet 192.168.0.1' (You will see a BusyBox shell prompt).

6) type 'iptables -D INPUT 1' at the # prompt (this disables SNMP blocking).

That's it, your router will now respond to SNMP requests on port 161. Get yourself a program like PRTG and hook it up, remember that your community string is 'public' but PRTG should default to that anyway.

Of course if your router has a different IP address simply replace 192.168.0.1 in all the steps above with whatever your router's IP is.