Can pppoE break a DSL sync?

[skywalker007]

Not sure if the topic attracts a reader but let me give it a try:

I have, since a few months, the problem that my VDSL connection breaks once or twice a day.
My setup so far was OPNsense with pppoE on WAN -> Draytek Vigor 165 as modem.
It's not only the pppoe that breaks, it is the DSL wich re-syncs and then 2 min later the connection is back.

I replaced the modem - > same issue.
I called the ISP, they came and changed the port in the DSLAM and also the a different pair of cables.
-> same issue.
So I bought an original Telekom Smart 3 router, put it into modem only mode and tried that -> same issue.
So finally, I put the Telekom Smart 3 back into router mode, reconfigured OPNsense to not use pppoe but just send packets to the Telekom router. -> Now the connection is stable.
How can that be? Did OPNsense 20.7 introduce some major changes to the pppoe client that brakes my connection? I can't imagine. I am a bit out of ideas and want my old setup back but I need to get it stabilized (was running well before). I can't really say if this started with the 20.7 upgrade, but it falls into the same timeframe.
Any feedback, suggestions are highly appreciated!
cheers, Till

[chemlud]

PPPoE and BSD can be pain, have a look at the interwebs.

Have you tried different FWs for the Vigor? I have only a 130, but there are frequent updates and tweaks for different VDSL "versions". If you log into the Vigor in modem mode, there are some pages on quality of connection etc. that might provide some insight (when the connection get's lost)....

[schnipp]

Generally, PPPoE cannot break the DSL sync because of different layers. But, in case the PPPoE issue triggers a software bug in the modem (e.g. hardware watchdog in case of a freezed kernel or software processes) DSL sync can break. So, the relvant questions are:

• How many different modem models and firmware versions are affected?
• In case of different devices, do they share the same code base?
• Does it break DSL sync or does it trigger a reboot of the device?

[skywalker007]

I tried different mdm flavors for the Vigor. And it doesn't trigger a reboot. Just a resync. One idea I had was trying to match the modem code in the Telekom device with the modem code in the vigor. Didn't try that. Though what struck me was that the Telekom in modem mode shows same behavior. Only in router mode the connection is stable. So weird.

[schnipp]

Are the boxes able to export a debug log? In case not, you can try a fritzbox and check if the sync is stable. If not you can check the details in the gui and export a log.

[skywalker007]

The Telekom boxes are quite limited with what they can log. A Fritzbox I don't have. Hmm.

[skywalker007]

So there updates to this,
After I ran the Telekom router for a while, it updated its firmware twice and with that the modem code.
So I reconfigured it to pure modem mode, reactivated pppoe on the firewall and it seems to run stable.
So the problem seems to  be the modem codes offered by draytek on the Vigor 165 modems. None of them seemed to run stable on my line. I'll give it another try with different firmware flavours of the Vigor.