Problems connecting a router (ASUS RT-AC88U)

Hey Everyone,

I do occasional tech work, and set up for some people. I recently was asked to set up a router after there was some issues with the device.

The router is an ASUS RT-AC88U and it is not able to connect to the internet when wired in. When tested on another network, the device works perfectly fine. I have done most the basic trouble shooting, checked the wired connections, went out to the modem, made sure everything was connected, making sure the router IP is unique, and giving it a set range to assign devices. The router would read connected to the internet, but on both Windows and Linux (Ubuntu 16.04) it would not transmit data outward (using ping tests) and the packets would get lost. I reset all the router settings, and was even able to detect the ISP while connected to the router from my laptop.

The router is on the latest firmware, and fully up to date as a previous tech had done that.

Oddly enough, it works as a daisy chained device, with DHCP settings turned off, through their previous router.

The connection type is Fiber Optic, and I'm not sure if that would cause an issue.

The router is in the "router" mode.

Any help anyone could provide would be greatly appreciated.

is the internet gateway? if so has the isp been informed of the change? many isp's filter by MAC address so this could be a problem. or it just shows up as a (to them) "unknown device" and is therefore blocked.

I did spend sometime with Consolidated Communications, and they claim that the issue is not on their end. I may spend some some time talking with them to figure this out.

make sure NAT is turned off

you might try cloning the original routers mac address, if it works call the isp and have them change to the new router. if not, you may still need to call, as they might identify the original router in a different way, and need to update their servers to recognize the new router.

I'm not expert on network configurations (I do that when needed). But, I would expect that since the other router have DHCP then ASUS should be either switched to "bridge" mode, or simply had its own DHCP and NAT in "router" mode.
As part of DHCP configuration usually a "gateway" device is set the same as DHCP server and since this is not consistent with ASUS working as a "router" in between it might be the root of the issue (I assume that ASUS has some kind of DHCP pass-through enabled?).

advise you don't do this, you need NAT.

This should do the trick.

'Bridge mode' or 'AP mode' forward existing DHCP.

'Router mode' it runs its own DHCP.

if the ISP blocks ping (which happens), then using ping to troubleshoot would not be reliable.

meant at the very top level so the router they want to use will be handling NAT