New Asus Router "Your ISP's DHCP does not function properly"

[limitz]

So I am experiencing a strange issue when trying to setup a brand new Asus RT-AC86U router (I've tried two brand new RT-AC86U routers this week) where the routers quick setup attempts to determine the type of internet connection it is connected to via WAN and I receive the message, "Your ISP's DHCP does not function properly" (this shows up on both new routers I've tried). I also connected my PC directly to the ONT (I have FTTH by the way) and even then it cannot connect to the internet which shows, "Cannot identify IP configuration". After troubleshooting I am now certain that it's not a hardware issue as far as the two new routers and my PC.

I digress. I have zero issues with Sonic service coupled with my older ASUS RT-AC68U on Merlin FW nor official ASUS FW for nearly 2 years and still going. This older router always detects my sonic fiber connection via WAN <-> ONT. No problems here.

I do remember when I connected the first new RT-AC86U and ran setup it did detect internet and worked fine for approximately the first hour or two, and then after a reboot it wouldn't connect ever again until I sent it back to Amazon where they then sent me another new RT-AC86U which also refuses to connect to Sonic.

I am really wondering if my older AC68U's MAC address is permanently tied to my Sonic account or something over at Sonic HQ which is denying any new/unknown MAC addresses. I figured I would be able to swap out routers on the fly and not run into denial of services. Note: This router replaced Sonic's leased Pace router on the same day of FTTH installation.

Could this be some sort of DHCP lease issue either on my end or on Sonic's end? Do I need to contact Sonic whenever I am about to use a different router with their service and give them update MAC addresses? I remember I had to contact Comcast whenever I wanted to use different routers and MAC addresses.

BTW, I have tried many times, turn off router, unplugging power from ONT (leave off 2 minutes), turn off computer, plug power back into ONT (wait 2 minutes, all lights solid), turn on router (wait 2 minutes) and power on computer. In the end no change in behavior.

If anyone knows what's going on here and could reply I would greatly appreciate the help!
I am planning on contacting Sonic Tech Support by end of this week and see what they can provide for me and my odd issue.

Apologies for the long winded post.

Thanks in advance,
JT

[limitz]

Update - I called Sonic and turns out that the MAC table was completely filled (8 slots) on their end which caused my router to not 'handshake' properly due to not having any available slots within the MAC table. Thus not allowing connection of service.
Once he cleared my MAC table my new router connected instantly.

[soniclvr]

I'm having the very same problem often with AC66U and with AC68U.

Changing the setting of DHCP polling on the Asus from "aggressive" to "normal" seems to help somehow. But still doesn't completely solve my problem

[soniclvr]

Totally frustrated with constant loses of WAN DHCP IP address with Asus routers. Called Sonic yesterday and they reverted to tell me they don't support any other router than theirs. This is clearly an issue between however Asus does DHCP and the ONT that more people will be experiencing...

I'm switching back for the time being to the rental router which works ok, although AC coverage is worse and lacks features I rely on on my asus.

[dhbatzloff]

Several years later, this is still a problem, and the answer still worked.
I had simply plugged the cable out ot the modem to my Orbi router, forgetting that it was in bridge mode, so it filled up Sonic's dhcp slots instantly. I called sonic, and the router was working before she could tell me to restart the modem (which wasn't needed)