Seat Arosa Starting Problems: With or Without WFS?

Hello.
A Seat Arosa 1.7 SDi, 1998.
With 130,000 km mileage and 90,000 km operated on biodiesel.
VSSZZZ6HZXR003915, K44
It starts up and then turns off after a few seconds. The next time, it doesn't turn off immediately, but after 2 hours of waiting, it starts up again - and then turns off again.
The fuel filter was replaced at 60,000 km, 90,000 km, and 106,000 km. The return lines were also replaced. One of the diesel lines had swollen.
On Monday, I plan to check the diesel filter to see if it's full and to inspect the lines to ensure they are free of air.
To avoid searching in the wrong direction unnecessarily, here's my question:
Could a faulty WFS (Web Feature Server) potentially explain why it's suddenly shutting down?
Thank you for the answers.

Does that one have a WFS?

Yes

You're welcome, Mulle.
Should the engine, when the system is active, not briefly run and then shut off with each start attempt?

If it's grabbing, yes. Then the symbol should also be blinking. What does the memory say?

I only have the information above, and I haven't looked into it further, but I'm starting to doubt the WFS theory because there shouldn't have been any combustion noises after the first engine failure.
There was no mention of an AI advertisement, and he would definitely have told me (teacher)!
I suspect either a clogged diesel hose or a fuel filter. Air in the system seems less likely, because it would have stopped running again briefly. Could it be a faulty shut-off valve?

So, there's air in the hose!
Weasel or filter leak - thank you for the WFS information, .

I checked today:
The air bubbles in the transparent hose are caused by biodiesel that has coagulated or become contaminated.
When heated with a hairdryer, it becomes clear again! It hasn't frozen outside yesterday or today, probably around 5-8 degrees Celsius at night!
I took a sample.
Shouldn't the gas station owner be responsible for paying for the towing, emptying, and disposal?
Do I have a chance of success?