E3000 DHCP server issues?

Question

I recently purchased an E3000 and immediately upgraded to the latest firmware version,1.0.03 build 2 Sep 7, 2010 . I've noticed a few issues with the DHCP server.
First, some entries appear to drop out of the DHCP client table before their DHCP lease expires. This has happened with several Windows 7 clients and with a pair of Linksys WRT54GS routers that obtain their IP addresses from the DHCP server in the E3000.
Second, I have two Netgear GS108Tv2 switches attached to the E3000. When these switches are running firmware version 5.0.0.8 they can obtain IP addresses from the E3000, but I can't access them using a web server. When these switches are running firmware version 5.0.1.11 they fail to obtain IP addresses from the E3000. I suspect the DHCP client in these two devices has a problem and I have reported this behavior to Netgear, but I believe the DHCP server in the E3000 may also be part of the problem. Why? Because I connected the switches to one of the WRT54GS routers mentioned above and they were able to obtain IP addresses from the DHCP server in the WRT54GS, which is a model 7.0 running firmware versionv7.50.8 build 001, Oct. 5, 2009  .
Finally, a question regarding DHCP reservations with the E3000. When creating a DHCP reservation, does the assigned IP address have to come from the scope of addresses assigned to the DHCP server? For example, I have configured the start IP address for the DHCP server in the E3000 to be 192.168.1.64 and the maximum number of users to be 64. However, I have created reservations for IP addresses 192.168.1.10 and 192.168.1.20 for the two WRT54GS routers mentioned above. I have also created a reservation for two clients within the assigned range as well. All assignments appear to be working correctly, but I would like to confirm that both approaches are kosher.
Thanks in advance.

Answer 1

On 04/27/2011, I opened a case with LinkSys/Cisco support concerning lost DHCP Client Table entries on both my new E3000 V1.0 router (running firmware upgrade 1.0.4) and it's WRT54G V8.0 predecessor.  After several days of using WireShark capture traces, I was able to determine the entries were being dropped when an application on one of my four WinXP/SP3 systems sends a "DHCP Inform" packet to the router.  The E3000 (and WRT54G V8.0) responds with correct IP Lease information but deletes the client's entry from it's DHCP Client Table in the process.  My problem was supposedly referred to the support team in Irvine, CA about a week ago, after I discovered what was causing the table drop, but I have not heard from the Irvine team yet.  I will follow up on Monday for a status update. 
Oddly enough, the "triggering application" is MicroSoft's AutoUpdate process.  Once I configured MS AutoUpdate from "Check but do not download updates" to "Turn Off Automatic Updates", the AutoUpdate process ceased generating "DHCP Inform" packets and my system has not been deleted from the router's DHCP Client Table since then.  I have a total of four WinXP/SP3 systems behind the E3000, one is direct connected to an Ethernet port on the router and the other three are connected to the EG008W switch which is connected to a port on the E3000.  One of those three systems is occasionally connected wirelessly to the E3000 for long periods with no connection problems.  My NVidia nForce 730i tower is one of the systems on the EG008W switch and is the one that was being dropped from the DHCP Client Table (whether it was on the switch or direct connected to the E3000).  The system that is always direct connected to the E3000 is an identical NVidia nForce 730i tower and has never been dropped from the DHCP Client Table.
Please note that the client that was being dropped from the router's DHCP Client Table did NOT lose access to the Internet.  Repeated checks using Command Prompt "ipconfig /all" indicated the client still had it's IP Address lease.  Issuing a "ipconfig /renew" command resulted in the client being shown in the router's DHCP Client Table until the next "DHCP Inform" packet was sent and responded to by the E3000 (and WRT54G) router.
Concerning switch connection issues with the E3000 and some newer WRT54G wireless routers, I had a similar issue in March 2011 with a LinkSys SD2005 Gb switch newly connected to a WRT54G V8 and later my new E3000 wireless routers.  The SD2005 had no issues connecting to an older WRT54G V6 router.  A call to the Support line transferred me to the Cisco Engineering support team which confirmed connection compatibility issues with older switches and new LinkSys Wireless routers due to firmware changes in switch connection support.  I replaced my SD2005 with an EG008W Gb switch and have no problems with it on either the E3000 or the WRT54G V8 backup router.
Concerning the randomly assigned dynamic IP addresses from the E3000, from my perspective this appears to have started after the WRT54G V8.0 Wireless-G router firmware.  Not only does the E3000 definitely prefer the upper 10 IP addresses of the dynamic range but it ignores a client's request to renew a previously assigned IP address during the client's "half-life" IP Lease renewal process and usually assigns a different IP address.  This may part of undocumented identity protection policies.  I have chosen to use the E3000's DHCP Reservation function for my home based systems, both wired and wireless.  I do not use the DHCP reservation function for the new E3000 "Guest" wireless network.  Please note my use of DHCP reservation went into effect about halfway through my DHCP Client Table diagnosis process and had no affect on the issue except that I had reliable client IP addresses to use in ShareWare capture filters.
I apologize for the long dissertation, but after 40+ years in various mainframe/open-system positions, I have a well known penchant for documenting problems for future reference.