ASUS RT-AX86S - "Your ISP’s DHCP Does Not Function Properly"

[G-Funk]

Hello community,

I have recently joined NOW Broadband and am struggling to get my ASUS router working. I am using a TPLink TD-W9960 as a modem configured in Bridge mode and an ASUS RT-AX86S router. The config I have in the ASUS is using DHCP Option 61 with a working username and password. Whenever it tries to connect to the NOW service, I get an error stating "Your ISP’s DHCP Does Not Function Properly". However, if I configure my TP Link as a router with a Sky(MER) profile, it connects immediately. Both of these units were fully functioning on Sky Broadband.

I'm now double NAT'ing which is less than optimal. Does anyone have any ideas as to what might be wrong? Happy to share config screenshots if that helps!

Thanks

[Jayach]

I'm surprised you had to make any changes, as coming from Sky I would have expected it to just keep working.

When you are setting the TP Link up in modem only mode what options does it give for ISP in step 5 from here: How to setup TD-W9970 Router in Modem Only Mode? | TP-Link United Kingdom (assuming the setup on the TD-W9960 and TD-W9970 are similar)

[G-Funk]

Hi and thanks for your response.

The options on the TD-W9960 are slightly different as there is no "ISP" option. You can choose the modulation type of ADSL or VDSL instead, I have VDSL selected. Otherwise, my set up is as per the step 5 graphic. 

[G-Funk · Accepted solution]

We have a result!! After much playing around, it turned out to be an issue with the ASUS firmware. I had been running the latest (3.0.0.4.386_49599) but downgraded to an older version (3.0.0.4.386_41535) and it connected immediately. I then re-applied the newest firmware and it's kept the connection.