Did you replace the gnutella.net file, as shown at the start of this thread? If this thread's a bit confusing for you, have a look at the link below for detailed instructions.
If LW Will Not Connect

Remember that LW has to be completely closed before replacing the gnutella.net file, or deleting the preferences folder. Otherwise it's a waste of time.

Do you mean that you can't change from using UPnP within LW's options (make sure to click 'apply' & then 'ok' to save a change)? Or do you mean that you have UPnP set within LW's options, but can't change to UPnP within your router's setup pages? If your LW options are stuck, then deleting LW's preferences folder/s (see thread above) should resolve that.

You could also try changing ports. In LW tools > options > advanced > firewall config. Change LW's listening port to 65000 (or anything in the range of 49152 - 65535) > apply > ok.

If nothing above works (& you're sure that you've done things properly), if you're able to change settings within LW's options, you could also try port forwarding for your router.
Port Forwarding for the Westell 6100
LW's listening port, port in the 'manual port forward' box & port forwarded within the router's setup pages should all be the same number.

And please...no more smartass posts about "no real answers" etc or nobody is going to bother trying to help you any more...if one fix worked for everyone, don't you think we'd post it?
We don't work for LW. We give a number of fixes to try, because different users with different systems have different problems for different reasons.