Bandwidth monitor/port forwarding

I'm still trying to configure a 3rd-party program (PRTG) to
monitor traffic at the router level. I spent 55 minutes on
hold and ten minutes with MS support before getting cut
off, by accident...I hope!

It seemed we were getting close. The issue seems to be
'persistent port forwarding' settings under the 'security'
dialogue of the base station management interface. This is
the relevant help section from PRTG: "Make sure that UDP
access to port 161 (SNMP) is allowed and you will also need
the return path open. SNMP uses UDP not TCP, so SNMP
requires the use of UDP ports >1023 to the PRTG client side
so that the results can be sent back from the device to the
machine running PRTG."

So my question is - what *specifically* do I enter as the
inbound port(s), do I select UDP as the protocol, and what
are the 'private port(s)' values?

I am using a MN-700 on XPHome SP2 with firewalls disabled
(I'm behind the router, right?).

I think I'm very close! Any help would be greatly appreciated.