Hi,

I've got a CRS326 (v6.48) running in my setup. It is connected to a Draytek Vigor 130 Modem in bridging mode to maintain a VDSL connection over PPPoE.

I've setup a PPPoE-Client and it works quite stable but since a few months I experience sporadic outages in my WAN connection, mostly over night. Sometimes it happens multiple days in a row, but also it worked stable for the last week, or so. The last occurance was tonight. It is not directly reproducible and I don't see anything in the logs.

When this happens, the PPPoE client is still running but I can't connect to hosts outside my LAN. When I disable and enable the PPPoE client again, the connection is back instantly.

I first suspected the modem, but obviously, a reconnection with training on the VDSL side would require quite some more time...

I have no specific firewall rules on a timely basis.

Does anyone have an idea what could be the problem or give a clue for what to look for when this happens the next time?

Did you check if the problem occurs only on IPv4 or if it also affects IPv6?
I have an issue like that where the IPv4 IP on the PPPoE is sometimes lost, but the IPv6 address remains.
I added a small script to recover from that condition (it regularly checks if an IPv4 address is still present on the PPPoE and if not, it disables/enables it)
That is something I still need to investigate in detail and report to support.

I also sometimes experience an other issue (on another connection): sometimes when the PPPoE is down it won't come back up again unless I disable it for a couple of minutes.
That is a different issue, and it is caused by a bug in the ISP network. The modem/routers supplied by the ISP do not experience this issue because in such cases (when they cannot establish PPPoE) they drop the VDSL connection and re-train, which resolves the problem. With an external VDSL modem of course this does not happen.

So far I've disabled the ipv6 package, as Deutsche Telekom (so far) provides true dual stack internet...

So, as you say, you also experienced that but didn't look further into it, as you've found a workaround, right?

The workaround is a good idea and I will go for it as well, but I'd also like to understand, what is happening here...

I just checked: I have a system uptime of 14 days (I guess I updated to 6.48 that time) and in that period experienced 5 link downs on the PPPoE client...

A friend of mine with the older CRS325 and the same modem does not have any problems of that kind.

The fact that it happens during the night can hint in the direction that it is related to some service window.
E.g. there is maintenance in the transport network that leads to brief interruptions of the link or some loss of state in the transport network (comparable to NAT at the network level) from which it only recovers when the session is re-established.
One could argue that the MikroTik should automatically try to re-establish the PPPoE session when the IP address is lost.
And the ISP-supplied routers probably do that, so they don't get complaints from their regular users.

The fact that it happens during the night can hint in the direction that it is related to some service window.

Yes, I though that, too. But it only happens "mostly" during night time...

One could argue that the MikroTik should automatically try to re-establish the PPPoE session when the IP address is lost.

...or at least put some message in the log.

Very strange... I'll put some verbosity into the workaround script to see when this happens in future.

My script is like this:
This is scheduled to run every 5 minutes.
Of course a /log could be added as well, but the disable/enable is also logged.
You could also send a mail from such a acript.

Hi again,
for quite some days now, I again have the described issue, that the PPPoE client hangs. This time I checked:
- IP address is still present on device.
- Interface and default routes are also still present.
Restarting the PPPoE client instantly fixed the problem. Of course I received a new IP address. But there is no new training on the VDSL line, like when the DSL link is restarted.
Any ideas where to look further next time?

Sorry for coming back to this almost two years old post.

Currently I have exactly the exact same issue after switching from hex to RB5009. The router is running behind a modem connected to a DT VDSL line and from time to time the pppoe connection seems to "hang" (no more packets received from AC side) while it is still shown as connected with an IPv4 address assigned to it.

Did you find a solution for the problem?