I just couldn't give up, I followed the procedure below and it worked. No more DHCP error even on a reboot! 388.4 beta up and running! I slightly modified the original procedure........see below:
ISP's DHCP not functioning - Fix for ASUS Router owners (probably others)
I'm posting this to assist others with the same issue. I recently upgraded my Xfinity Internet to a higher speed and purchased a new modem to support 1000Mbps. I prefer to manage my own hardware so I purchased a Motorola MB7621 modem and after working with Comcast, I got the MAC address updated and confirmed I was online with internet exiting the new modem. Then the trouble started. My ASUS RT-AC1900P router that had been working swimmingly with Comcast as of 1 hour ago would not connect citing DHCP errors from my ISP. Neither the posts on this site, nor anything from ASUS had clear guidance on this issue. The only thing that eventually worked for me was:
1. Be connected to your wifi network even though it's not getting Internet, you need to access the router only at this point.
2. Access your router admin (192.168.1.1) and find out your firmware number and place to update it MANUALLY.
3. Disconnect from your wifi network and get online somehow. I used my ethernet cable because I had internet to my modem, you could use a hotspot or whatever, just get online.
4. You'll then want to visit ASUS website, go to support, find your device, and DOWNLOAD the latest firmware. Then unzip it and remember that file name and location. https://www.asus.com/us/support/
5. Rejoin your wifi network, yes, the one that doesn't have Internet.
6. Go back into the admin portal (192.168.1.1) and upgrade your firmware using the file you downloaded and unzipped.
7. Do a HARD reset of the router using the button in the back. For some reason, the reset offered through the admin portal didn't seem to work.
8. Let the router restart and join the network called ASUS (this is what you did when you bought it)
9. Once you join it will ask you to set up a new network. Follow the steps that you did back when you bought it (Automatic IP, not Static). at this point unplug modem
10. Reconfigure your network SSIDs because the reset wipes everything out.
11. Power on the modem
12. ASUS will detect the Comast signal, do the configs and get you online, nothing else for you to do.
CC
ISP's DHCP not functioning - Fix for ASUS Router owners (probably others)
I'm posting this to assist others with the same issue. I recently upgraded my Xfinity Internet to a higher speed and purchased a new modem to support 1000Mbps. I prefer to manage my own hardware so I purchased a Motorola MB7621 modem and after working with Comcast, I got the MAC address updated and confirmed I was online with internet exiting the new modem. Then the trouble started. My ASUS RT-AC1900P router that had been working swimmingly with Comcast as of 1 hour ago would not connect citing DHCP errors from my ISP. Neither the posts on this site, nor anything from ASUS had clear guidance on this issue. The only thing that eventually worked for me was:
1. Be connected to your wifi network even though it's not getting Internet, you need to access the router only at this point.
2. Access your router admin (192.168.1.1) and find out your firmware number and place to update it MANUALLY.
3. Disconnect from your wifi network and get online somehow. I used my ethernet cable because I had internet to my modem, you could use a hotspot or whatever, just get online.
4. You'll then want to visit ASUS website, go to support, find your device, and DOWNLOAD the latest firmware. Then unzip it and remember that file name and location. https://www.asus.com/us/support/
5. Rejoin your wifi network, yes, the one that doesn't have Internet.
6. Go back into the admin portal (192.168.1.1) and upgrade your firmware using the file you downloaded and unzipped.
7. Do a HARD reset of the router using the button in the back. For some reason, the reset offered through the admin portal didn't seem to work.
8. Let the router restart and join the network called ASUS (this is what you did when you bought it)
9. Once you join it will ask you to set up a new network. Follow the steps that you did back when you bought it (Automatic IP, not Static). at this point unplug modem
10. Reconfigure your network SSIDs because the reset wipes everything out.
11. Power on the modem
12. ASUS will detect the Comast signal, do the configs and get you online, nothing else for you to do.
CC