I might have a solution for the now and then network connection drop on the wdr3700.
I noticed that my network resources are still available during the drop, but the internet connection is lost.
After fiddling for weeks I found out what works for me:
In the lan and wireless lan settings, only set the DSP servers according to your provider's IP adresses. THat is in the Internet protocol (TCP/IP) section.
So leave the "obtain ip adress automatically..." alone (obtain automatic or manual pre-set. Not important here.)
And set the "Use the following DNS server adresses..." to your ISP WAN DSP server adresses. These can be found in the status screen of your Netgear router via www.routerlogin.net. Or via your ISP's connection manual.
SInce then, no more connectivity losses for me.