Aside from the cable modem you describe my environment perfectly. I have 5 PC's and 1 A4000D hooked into my Linksys and all work well. What address are you getting for your A4000? you should be able to see that by running IFCONFIG from the Genesis Bin folder. Make sure the IP matches what your network on the private side of the Linksys is. To show example my internal network is 192.168.100.x. I had to manually configure an IP for the A4000 by editing the startup scripts for Genesis.
