Bridged by XB6, my router cannot get DHCP

[ckl]

Hello.

I just got the XB6 yesterday, hooked it up, and got it activated. I confirmed that my internet was good and getting the proper download speeds.

Then I turned it into bridge mode and hooked it up to my Asus rt-ac66u router. Immediately, I ran into trouble, it said something like cannot get DHCP from ISP and there was no internet. I finally got it working after searching around the internet for a while. Apparently, in the Asus admin page, there is a WAN section with "Special requirements from ISP". I got it working by putting in the MAC address of the router and changing the dns frequency to normal.

This this morning, the same thing happened. I had to reboot the router to get to work again. I don't know what I should be filing out in this section. Here are the fields:

SPECIAL REQUIREMENTS FROM ISP

1. Host name: __________

2. WAN MTU: 1500

3. MAC Address: xx:xx:xx:xx:xx:xx (what should I fill in here? the MAC of my router or the XB6?

4. DHCP query frequency: Normal Mode/Aggressive mode (set to normal)

5. Manual clientid (Option 61):___________

6. Manual Vendor class (Option 60): _________

7. Extend TTL value: Yes/No : No

8. Spoof LAN TTL Value: Yes/No: No

Can anyone explain why this is happening and how I can fix it?

[shaw-tony · Accepted solution]

@ckl that is very odd. While the modem is in bridged mode, are you able to test a direct ethernet connection from the modem to your PC to see if there is an internet connection? If so, the router should be able to pick up the IP. If your PC is able to grab an IP, you may need to factory reset your router for it to work.

[ckl]

When this happened yesterday, I unplugged my router and then plugged my computer directly into the XB6. Was able get an IP address and was on the Internet. I've played around with the settings on the Asus router and hopefully, it doesn't happen again. If it does, I will have to look at another setup.

[ckl]

I think I have resolved my issues with bridge mode and my Asus router, but in the case that it is not stable, I need to look at other solutions besides bridge mode. What would be the difference between:

1. Put the XB6 in bridge mode and use my own router (what I'm doing now).

2. Put the XB6 in router mode and put my own router in the DMZ?

3. Put the XB6 in router mode and use port1 as passthrough to my own router. (if this option exists as I can't check without turning off bridge mode).

What option 2 & 3 work like bridge mode?

[shaw-tony]

@ckl 
1. This is a standard way to set up the modem/3rd party router.
2. This is also an available option but it is not supported. I've seen some success with other users configure their XB6 this way. (Acts similar to IP passthrough)
3. XB6 does not have any IP Passthrough capabilities, you will have an IP mismatch which will cause an intermittent connection. 

[nyarlathotep888]

I'm having similar issues with the same router as well as a RT 86U

I started having issues when I transitioned from the Hitron modem to the new XB6. 

Can you tell me what you did to resolve your problem?

[ckl]

I don't remember exactly what I did but here's what I have in the WAN section under the Internet Connection tab:

At the bottom is where I changed some values:

Special Requirement from ISP

Hostname: <blank>

WANT MTU: 1500

Mac Address: <blank>

DHCP Query frequency: Normal Mode

Manual Clientid (Option 61): <blank>

Manual Vendor Class (Option 60): <blank>

Extend the TTL Value: Yes

Spoof LAN TTL Value: No

Not sure how this differs from the defaults but this the section I was playing around with when I got it working.

[Agbi]

Had this issue as well.. Just leave every as default (Automatic IP), put dhcp query frequency to normal and click on "MAC Clone" to get mac automatically.. Apply and it should start working provided shaw is already on bridge mode.. 

[mdk]

It is the cable-modem that "enforces" the number of IP-addresses that you can use.

If your Shaw plan only gives you one IP-address, then switching the cable-modem from "router" mode (where the "public" IP-address is assigned according to the MAC address of the network-adapter inside the device) to "bridged" mode (where your own device, with its own network adapter, and a different MAC address) sends the DHCP-request to Shaw, to try to obtain a "public" IP-address. But, if Shaw's configuration of the cable-modem only allows one IP-address, your device (either your own router, or your computer) will not receive an IP-address.

After setting the cable-modem to "bridged" mode, the "trick" here is to power-off the cable-modem, to reset the "enforcement" counter to ZERO IP-addresses, and then do a normal power-on.  In "bridged" mode, your device (router or computer) will then obtain a "public" IP-address -- the cable-modem will not try to obtain an IP-address for itself.

If your Shaw plan allows two IP-addresses, then changing the cable-modem from "router" to "bridged" mode, without a power-off/power-on, then that "enforcement" will let you use two IP-addresses.  Note that the IP-address assigned to the cable-modem when it was in "router" mode will eventually (1 day?) "expire".  After that expiry, connecting a second computer to the second port on the cable-modem will allow that computer to obtain and use a second IP-address.