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New Contributor NJ_
New Contributor

ISP's DHCP did not function properly - cannot connect to the cable modem

Hello All. My current setup: Optus cable internet, Sagemcom F@ST 3864V3 HP modem, ASUS RT-AC5300 router. 

I have been using the ASUS router for better wifi coverage with about 16 devices connecting at any time. This has been working fine for over a year now. About two weeks ago, the WAN connection from the ASUS router to the cable modem stopped working and therefore no internet connection is available. In the ASUS router's log, I see the message "WAN Connection: ISP's DHCP did not function properly.". I have tried various troubleshooting, including a firmware upgrade, factory resets etc on the ASUS router, but no success. The Optus supplied Netgear CM500V router still works as expected. Has anyone else experienced similar and has any suggestions? Thank you.

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Honoured Contributor
Honoured Contributor

Re: ISP's DHCP did not function properly - cannot connect to the cable modem

I take it you are not on the NBN?

Can you remove the Optus all together and plug straight into the Asus?

You've tried other Optus ports for the connection to the Asus (also replaced the CAT5 cable between them? )

Otherwise I can only suggest try the router at a friends house or get Asus to have a look at it.

Peter Gillespie
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Regular Contributor
Regular Contributor

Re: ISP's DHCP did not function properly - cannot connect to the cable modem

Have you powered down the CM500V HFC Modem - that device gets the Optus DHCP assigned WAN IP address and passes it to the 3864V3HP Modem. Also your Sagemcom 3864V3HP modem may have received a remote firmware update, have you tried to do a Restart from within its GUI Menu or do a Factory Reset if that doesn't improve matters. 

Not sure what firmware is current on the 3864V3HP - I have seen 10.70.1_F@ST3864V3HP_Optus but on the previous 3864V3AC 10.96_F@ST3864V3AC_Optus, making me think there could be a later version for the former. Maybe one of the readers could confirm.

You should be able to verify the CM500v WAN IP address in the 3864V3HP GUI screens and see the 3864V3HP IP address as the Gateway in your ASUS GUI Screen.

I take it you have CM500V ----WAN 3864V3HP LAN -----WANASUS (two networks) rather than CM500V ----WAN 3864V3HP LAN -----LANASUS (one network) .

If you connect a PC to the 3864V3HP, can you connect to the Internet?  Do wired and wireless devices on the ASUS fail to establish a link to the Internet, or is it just wireless devices?  

New Contributor NJ_
New Contributor

Re: ISP's DHCP did not function properly - cannot connect to the cable modem

Thanks petergdownload. I'm not on the NBN, but on the Optus Cable HFC network, described here https://www.optus.com.au/shop/broadband/home-broadband/network/cable

I think I described my setup in the first post incorrectly. My setup is Netgear CM500 modem connected to the Optus HFC cable wall point with a coax cable. The ASUS router's WAN port connected to the Netgear modem's ethernet port. 

I think the WAN port on my ASUS router is dead. When its connected to the Netgear modem, the ethernet light on the modem doesn't come on at all. However, when I connect the Optus supplied Sagemcom router to the Netgear's ethernet, the light comes on and works correctly. Also, I tried the dual wan setup on the ASUS, by using one of the LAN ports to connect to the Netgear, and that worked after I re-started the Netgear. So it points to the WAN port on the ASUS not working. Not sure how I can confirm this. Thanks.

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New Contributor NJ_
New Contributor

Re: ISP's DHCP did not function properly - cannot connect to the cable modem

Thanks Mkrtich. My setup is CM500V ---- WAN ASUS.  I think the setup I described in my original post was not correct.

The CM500V----WAN Sagemcom works.  Ethernet light on the CM500V comes on straight away when the ethernet cable is connected to the Sagemcom

CM500V ---- WAN Sagemcom ----LAN ASUS (in bridge mode) works

CM500V ---- WAN ASUS doesn't work. The ethernet light on the CM500V doesn't come on at all in this setup.

I think the WAN port on the ASUS is dead. Don't know how to prove this for sure.

 

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Regular Contributor
Regular Contributor

Re: ISP's DHCP did not function properly - cannot connect to the cable modem

Yes looks suspect and most unusual - have you checked the WAN Settings page in case a the firmware upgrade changed any previous settings e.g.  is PPoE set with your Optus User ID and Password?

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