ADSL PPPoE reliability issues, ISP blames OPNsense

[spyware-avoidance]

I have just started using OPNsense for about a month or so, but last week my ADSL connection died due to problems with the line. Yesterday a technician visited the site and seems to have fixed the obvious line issues.

However the PPPoE connection dies once every few hours, and my internet goes offline. ISP blames the OPNsense and is unable to troubleshoot the issue on its own. They are trying to push me to dismantle my network and switch to using their modem and Wifi, and McAfee "business protection" whatever garbage they want to force down my throat.

It is also important to note that OPNsense has been working fine without any reliability issues for a couple of weeks before the line phone line died. I don't believe that the disconnection issue is due to OPNsense, although I may have possibly misconfigured something (again, I'm new to OPNsense and not completely familiar with the system yet), and we are just seeing issues now.

I have been trying to extract as much debug logs on the PPPoE connection to figure out what the system observes that is causing the disconnection, and for the most part I can't really make heads from tails of this.

I have attached the logs. Is there anyone who would be willing to provide a second set of eyes and can possibly explain what may be going on please?

[EdwinKM]

In the past i had ADSL, switched to fiber. The distance to their serverspace is long and had regulary problems:
* once had a own modem/router that caused the DSLAM (ISP side) to crash. Engineers had to drive to the server space to reset
* Modems try to train to the max. This made my connection unstable. Had to ask the ISP to limit the MAX connection

I think only you can determine the issue. Start with their hardware. Is this stable?
Use their modem and opnsense. Is this stable?

[spyware-avoidance]

I think I may have solved the problem. I had applied a few settings that I reversed and the issue seems to be gone since it has been stable for more than 12hrs now.

I had attempted to enable multi-threaded processing and power management for the system, and that coincided with the line going bad. After the line was fixed by the ISP, the stability issue remained until I reversed these changes.

I did not come up with these settings myself. I have a machine very similar to a "Procteli" (except mine has Intel NICs and a 10th Gen i5) and this was their recommended optimization for PPPoE found here:
https://protectli.com/kb/pppoe-and-opnsense/

Under System > settings > Miscellaneous
Removed checkmark for "Use PowerD" (disabled the setting)

Under System > Settings > Tunables
removed tunable "net.isr.dispatch" (differred) and "net.isr.maxthreads" ( 8 ).

I do not know why or how this will cause interface timeout (which is the only suspect I have from the logs) when the power was set to HiAdaptive, and later was changed to Maximum. I do not know enough about what the tumbles do or if they will also cause problem, I just don't want to mess with the network and cause outages again.

I am getting a second internet service being brought to my site since internet availability has become somewhat mission-critical for us. The second ISP is using cable, and I sure hope that I will not screw up another thing when trying to set up Dual-WAN and driving myself crazy.

Edit: Unfortunately fiber to home and even traditional phone line and cable internet coverage are very spotty in the place I live. 400m from where I live they have fiber, but it has been 10 years and will not bring new fiber 400 m towards us. I don't think it will ever happen, because the two monopolies here have all the power to do whatever they want... so I am stuck with what we can get here for whatever they charge for it.