RV082: Router-behind-router DHCP issues

[nbaker01]

Hello, I have UVerse, but I have my home network behind the RV082. I have disabled the firewall on the UVerse gateway for the RV082. On the RV082 I have a pretty simple setup:

- DHCP disabled (another server provides DHCP on the home network)

- No Firewall rules except the default ones (block all WAN, enable all LAN)

- A few port forwarding rules enabled

Occasionally I see client devices with IP addresses issued by the UVerse gateway ... I didn't think this was possible? Should I create rules to block DHCP/DNS/WINS etc. through the RV082 to the "WAN" (i.e. UVerse LAN)?

[mpyhala]

Nick,

If the firewall is enabled on the RV082 and it is in NAT (Gateway) mode, it is not possible for DHCP broadcasts to pass from the WAN network to the LAN network. Does the Uverse have wireless? Is it possible the devices are getting an IP wirelessly?

Also, do you have a second subnet in the RV082 that matches the Uverse LAN?

- Marty

[nbaker01]

Hi Marty,

The UVerse gateway does have wifi enabled, but a different SSID and password than what I use behind the RV082, so this can only be joined intentionally.

Also, I only have one subset on the RV082 LAN (the UVerse LAN has a different address range as well for its LAN).

Problem is that this seems to only happen to certain devices - I've run Microsoft's Network Monitor and checked for rogue DHCPs and nothing on the PCs anyway, but some of my network cameras and new "smart" CE devices only seem to be happy with static DHCP. I don't know if these are doing some IPv6 tunelling, or something like that that is messing them up (I do not have IPv6 enabled on my LAN). The rogue DHCP assigment was IPv4 though and matched the UVerse LAN (and this device didn't have wireless anyway), so I'm kind of at a loss.

Nick.

[mpyhala]

Nick,

To confirm whether or not the DHCP is from the Uverse, change the IP address and DHCP scope to something different like 172.168.88.0/24. If you see an address from that network, then you will know for sure.

- Marty

[nbaker01]

Correct, this is how I found that this was leading to my connectivity problems. The UVerse subnet is xxx.yyy.1.0/24 and the RV082 subnet is xxx.yyy.0.0/24. I saw an address in the xxx.yyy.1.0 scope and therefore started suspecting some rogue DHCP activity.

[mpyhala]

Nick,

Can you turn DHCP off on the Uverse device?

- Marty

[SamirD]

Strange.  Any way to get us a network diagram?

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