PPPoE Ping Spikes

I've recently moved from a VM internet connection to a FTTC connection with Onestream.

My TP-link AX20 router worked well with the VM connection with the VM SH3 in modem mode.

Now with Onestream I have a TP-Link TD-W9970 v4 providing the VDSL2 modem function.

Initially I had the W9970 in bridge mode with the AX20 doing the PPP bit. The TBB Quality monitor showed this...

Bridge Mode

Even when my broadband was not being used some constant ping spikes.

So I reconfigured the W9970 to do all the PPPoE stuff and configured the AX20 to a static IP (Double NAT with the AX20 in the DMZ of the W9970.
Now the TBB Quality monitor shows this ...

Double NAT

My conclusion is that the AX20 does not do PPPoE very well.

Question - has anyone else seen this type of problem?

We are possibly going to get FTTP in the next 6 months - will I still have to use PPPoE on FTTP connections or is DHCP used so I can keep my AX20?

Thanks.

Lots of ways you can do this. I would try to maintain the Line Connection and Routing functions within the one box.

The second box I would not connect via double NAT [Layer 3]. Better to connect the 2 boxes LAN to LAN [Layer 2]. If you do this, you need to make sure that

• they are both on the same IP subnet
• the LAN side IPs are different on the 2 routers
• there is only 1 DHCP server active

As for FTTP, it can be DHCP or PPPoE according to ISP. I am on PPPoE and all is fine - the small no ping blip is a reboot I did for a config change.

Edited by DFScale (Mon 27-Oct-25 17:31:40)

In reply to a post by DFScale:

Lots of ways you can do this. I would try to maintain the Line Connection and Routing functions within the one box.

The second box I would not connect via double NAT [Layer 3]. Better to connect the 2 boxes LAN to LAN [Layer 2]. If you do this, you need to make sure that

• they are both on the same IP subnet
• the LAN side IPs are different on the 2 routers
• there is only 1 DHCP server active

As for FTTP, it can be DHCP or PPPoE according to ISP. I am on PPPoE and all is fine - the small no ping blip is a reboot I did for a config change.

So, put the AX20 into access point mode?
Could I still use the VPN server on it in this case?

I've done some more testing on the bridge ping issue and pretty much shown the AX20 to be the culprit.

Connected a Windows laptop with a PPPoE config directly to the W9970 and got this...

AX20 then Laptop then AX20
The bit in the middle is the bridge to the laptop.

So the W9970 seems fine in bridge mode.

In reply to a post by Eeeps:

So, put the AX20 into access point mode?
Could I still use the VPN server on it in this case?

Sorry not to be much help on this. Effectively you will use it as an an Access Point port if you attend to the points I raise. A quick look at the manual suggests if you put it into Access Point mode you can connect via the WAN port which is now on the LAN, but do your own research. As for the VPN, I am unsure, although I would expect the manual to say if the VPN was not available in Access Point mode.

In reply to a post by DFScale:

In reply to a post by Eeeps:

So, put the AX20 into access point mode?
Could I still use the VPN server on it in this case?

Sorry not to be much help on this. Effectively you will use it as an an Access Point port if you attend to the points I raise. A quick look at the manual suggests if you put it into Access Point mode you can connect via the WAN port which is now on the LAN, but do your own research. As for the VPN, I am unsure, although I would expect the manual to say if the VPN was not available in Access Point mode.

Turns out the VPN server is not available when the AX20 is in AP mode. However...

Disabling the NAT function on the AX20 turns it into a standard router and crucially leaves the VPN and firewall available.
Connect the W9970 to the WAN port of the AX20.
Make sure the two subnets are different and add a route to the W9970 for the AX20 LAN subnet.

PPPoE and single NAT on the W9970.
VPN + firewall on the AX20.
result.