From last night my PPPoE is not working anymore on RB951-2n.
The router constantly connect and disconnect.
I contacted my iSP and there are no restriction from their side. The PPPoE connection works fine if i conect the ethernet cable directly to my laptop. I replaced the power supply but no positive effect.

So what could be the problem?

Why is your ether1 interface going up and down? Is it supposed to link at 10Mbps? Or should it be 100Mbps?

Did you enable the "Dial on Demand" option in the PPPoE client interface? If so, unset it.

What ros version? Lately specific version had problems with pppoe. I can remember which one.

Can be port or cable or modem(if used). Change the cable, use other port and check the device on other side of the cable.

da89ni says it works as desired with the Ethernet plugged into his laptop. From the phrasing, I believe that means the same cable was used in both setups. That would tend to rule out the modem and the cable.

Given that interpretation of the original post, I suspect configuration, software bug, or bad port on the RB951-2n, in that order.

A quick test to rule out hardware would be to change the parent interface of the pppoe-client interface.

The situation is very strange, I am aware of that. Let me summarize again the behavior:

There is no internet access on any device connected to RB951-2n. In LOG there are constant connecting and terminating entries. This is not a new installation, with this configuration router is running for more than a year (only routeros version was regularly updated). Curent RouterOS version used is 6.33.3. I tested the gateway on ether1 and ether5 and the situation is the same.

I called my iSP provider and they told me that there are no restriction in using a router but they can't offer me support for router configuration, I must connect the external cable (provided by iSP) directly to a PC and if there is no internet access then a ticket will be opened considering that there is a problem from their side.

When i connect the external cable (provided by iSP) directly to a PC and use DialUp PPPoE (in windows 10) the PC connects and internet works fine. So... the conclusion is that cable and service are ok.



I wold like to say once more that this situation occurred Friday evening without any intervention to the setup. I just noticed that internet access is not working and checked the LOG. The router is using this setup for more than a year.... Normally my first suspicion was for the iSP but because Win10 DialUP PPPoE is able to connect the problem i think is back to router side (or somewhere in between ?!).

I tested today with another router (TP-Link). The behaviour is almoust similar. TP-Link router remain connected but display error message "No interbet acces" in system tray.

Because Win10 DialUp PPPoE works fine, only routers have problem connecting i start to draw the conclusions that problem is in the settings somewhere...

I keep searching for a solution and i discovered that iSP is allocating me v4 and v6 iP.
Is it maybe possible that iPv4 to be the problem and iPv6 to work properly ?
This is a screenshot from my Network Connection Details when my cable is pluged directly into PC and a screenshoot from http://whatismyv6.com/

After further investigation i find out the following: my iSP is providing internet service over dual stack IPv4/IPv6 PPPoE server. Clients who use router labeled with IPv6 via PPPoE + DHCPv6 PD should have no problem accesing internet service.

So for the moment i think i should reconfigure my router as client for dual stack IPv4/IPv6 PPPoE server. But how do i do that?

Dani, the fact that your ISP gives out a dual stack access does not mean you need to use it.

RCS/RDS handles out IPv4 access via PPPoE in a standard fasion. The IPv6 part comes later as a dynamic DHCPv6 /64 PD, so for the moment you can leave it off and it will not bother you.

Just be certain to have NO Service or AC name set in you PPPoE connections settings, just the user name and the password, "Use peer DNS", "Add default route" and all authentication methods checked.
Also check your connection profile so that IPv6 is "yes" (not "required"), compression is "default" and encryption is "yes" (not "required"). And I would downgrade to 6.32.3 (latest bugfix).

check the MTU and L2 MTU on your physical WAN interface are set and match with the ones advised by your ISP (on your logical pppoe interface)

I had a similar issue, and when I set them up the same it all worked.

I downgraded the routeros to v6.32.3 (stable release) but stil no fix. PPPoE is constantly connecting/terminating. For the moment i can only access internet by connecting the external cable directly to my PC and using Win10 PPPoE client. I still can't draw the conclusion what is the problem... ?!

check the MTU and L2 MTU on your physical WAN interface are set and match with the ones advised by your ISP...

Where i can find the correct MTU and L2 MTU values?

click interfaces - then double click your physical WAN interface - ether1-gateway, on the general tab, try setting the MTU and L2 MTU to 1480