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Public IP ''Your ISP DHCP does not function properly'' fixed - but how?

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Windsbee

Occasional Visitor
I'm just trying to wrap my head around this:

I was trying to setup a OpenVPN on my Asus router and successfully connect to it from my iPhone outside of my network, and after days of troubleshooting, it seems like the fault was because my ISP is using CG-NAT.

So I got a public IP (ipv4) from them. They wanted $5 a month for one but I told them to pay an additional monthly fee after the trouble I went through is not my style, so they gave me a public IP for free.

They asked me to give them the MAC address on the back of my router (1), even though from what I've read I'm supposed to give them the MAC address that can be found at Control Panel - Network and Internet - Network and Sharing Center - Change adapter settings - right click on ethernet and hit status - details - and there you can find the physical address (2). But oh well, I gave them the MAC at the back of the router.

After doing so and restarting the router, on Network Map in the router settings it said: ''Your ISP DHCP does not function properly.'' No internet connection. I told my ISP this and they had no clue what to do. They tried MAC address number 2 but said they couldn't find it in their logs.

After doing some research, I went into WAN and at the bottom pressed MAC clone, which automatically entered MAC address number 2, found in the control panel. Changed DHCP query frequency from aggressive to normal, and hit apply. This made the internet work again, but the IP address was the old 100.65.xx.xx CG-NAT.

They told me MAC number 2 had suddenly popped up in their logs, and they switched to that one, but it went back to ''Your ISP DHCP does not function properly.'' No internet.

It was getting late and ISP told me I had to call back tomorrow to continue the troubleshooting with them. I asked them to switch back to the other MAC (1) on the back of the router so that I at least could have a wi-fi connection during the evening.

I sat and read a few forum threads, and found someone who went into LAN - then IPTV, and changed ISP profile from None to Manual setting, and then on Internet VID, entered ''2'', and clicked apply. So I did and now, out of the blue, my WAN IP is a public IP, that matches the IP I get on https://whatismyipaddress.com/

I tried setting up a OpenVPN and sure enough now it works. Hurrah!

The question is, why does it work? I could call back my ISP but honestly, I don't think even they'll be able to comprehend it, as they told me to try to work this over with Asus instead.

Which MAC address should they get, MAC address 1, or 2? 1 works, I know that but why do I read everywhere that they should get MAC 2? Hell, even their own guide said I should give them MAC 2. What if I call them up and ask them to switch to MAC 2, what then? Will it still work?

What does the MAC clone thing do? It enters MAC 2 automatically, why? Why MAC 2 and not MAC 1?

The whole LAN - IPTV - Manual - VID 2 thing. Why did this fix it finally? I went back into it, removed the ''2'', applied, and now it still works, and I have a public IP. How?
 
It can sometimes take a while for the old WAN IP and its associated MAC address to be "unregistered" from the ISP's equipment. Usually the simplest way of doing this is to power off the modem and the router completely. Then wait a while (5 to 30 minutes) before powering things on again.

It is the MAC address of the device connected to the cable modem that needs to match that registered with your ISP. Obviously in most cases this will be the MAC address of the router. You wouldn't normally use the MAC Clone feature unless your ISP requires that you use a specific MAC address.

The "VLAN thing" was probably just coincidental (unless your ISP requires it) and it was just the constant rebooting that eventually fixed it.
 
power off the modem and the router completely. Then wait a while (5 to 30 minutes) before powering things on again.
I waited for a total of 2 hours and nothing happened until I started manually tweaking the settings.
It is the MAC address of the device connected to the cable modem that needs to match that registered with your ISP. Obviously in most cases this will be the MAC address of the router.
Ahh brilliant, thanks!
and it was just the constant rebooting that eventually fixed it.
Yeah, maybe. Oh well, I can't explain it but hopefully someone else with similar issues will come along one day and see this thread.
 
I waited for a total of 2 hours and nothing happened until I started manually tweaking the settings.

Ahh brilliant, thanks!

Yeah, maybe. Oh well, I can't explain it but hopefully someone else with similar issues will come along one day and see this thread.

Agreed with the other poster - often the tech support doesn't realize they must release your old lease before you'll get a new IP. Depending on the ISP, this can take quite a while. During all your troubleshooting, its possible/likely it just finally expired.

If you've given them the MAC of your computer, then you will need to keep that cloned in the router for this to keep working. If you don't want to worry about that, you can manually release your lease (cycle the WAN to off in the GUI), call them back and have them change it back to the MAC of your router WAN, wait a couple mins, then cycle WAN back on. But not a big deal.

I doubt the VLAN thing is related, that would be just to get your TV or phone working, the internet portion is almost always on VLAN 1 and untagged anyway. Just coincidence as already mentioned.
 
I waited for a total of 2 hours and nothing happened until I started manually tweaking the settings.

Ahh brilliant, thanks!

Yeah, maybe. Oh well, I can't explain it but hopefully someone else with similar issues will come along one day and see this thread.
The vlan thing could been solved because of a sort of refresh sequence.
Everything on the asus routers are vlans, thats why they can make guest accounts or dual wan.
I can immagine that something was wrong with the vlan of the wan interface , and by changing the iptv vlan, it probably has launched a full refresh
I had similar problems and solutions.

For example if i have a dual wan and put a mac adress in on the primary wan, then i cant get a dhcp anymore.
Removing the mac adress doesnt help to get a dhcp back
However, if i disable dual wan and re-enable it, by magic both wans get IP's again...
So probably when configuring dual wan I also trigger some base configuration which in turn repaired my problem.

I'll now open a ticket with asus to see what is going wrong when I enter a mac adress
 
The vlan thing could been solved because of a sort of refresh sequence.
Everything on the asus routers are vlans, thats why they can make guest accounts or dual wan.
I can immagine that something was wrong with the vlan of the wan interface , and by changing the iptv vlan, it probably has launched a full refresh
I had similar problems and solutions.

For example if i have a dual wan and put a mac adress in on the primary wan, then i cant get a dhcp anymore.
Removing the mac adress doesnt help to get a dhcp back
However, if i disable dual wan and re-enable it, by magic both wans get IP's again...
So probably when configuring dual wan I also trigger some base configuration which in turn repaired my problem.

I'll now open a ticket with asus to see what is going wrong when I enter a mac adress

Not exactly, guest wireless only recently started using VLANs for GW1, and GW2 and 3 still share the same VLAN as LAN (prior to 386 code, all 3 guest used VLAN 1 along with the LAN).

I don't use dual WAN so not sure if that uses two different VLANs or not but there are other ways to accomplish it. With single WAN the port is defined in VLAN 2 but sent to the CPU without any VLAN tag so essentially it is just separating the port out. Oddly it does tag the LAN VLAN 1 to the CPU (vlan 1 should really never be tagged) so a bit of a strange setup there.
 

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