ᐅ Sewer connection at the property boundary

That was more or less clear to me, but still, there can't be a general ban on wastewater pipes at the property boundary (unlike with above-ground buildings). It was already mentioned that you should be careful when digging there.

You can’t build too close to the boundary, or the fence will fall within it.
But it sounds like an easement (right of way, access, and utilities) of 3.5m (11.5 feet) width and 40m (131 feet) length.
Alongside sewage, there also needs to be water, gas, electricity, cables (TV or fiber optic network), video intercom and doorbell with chime, 220V gate motor, and pathway lighting, and during construction, it may even serve as a construction access road for 40-ton trucks.

Hello Nida35a, it "only" has to include video, doorbell, buzzer, and pathway lighting. I will get all other utilities elsewhere. It won't be a construction access road either.

Nida35a schrieb:

You can’t build too close to the border, or the fence will end up inside your property.

Somehow, I have to prepare the path up to the neighbor’s fence so that I can later pave a walkway there...

For a path, you might dig about 40 cm (16 inches) deep. The foundations should be deeper, so it’s not a big issue for the short duration.

A trench is usually about 1 m (39 inches) deep and therefore more challenging.

Choose a convenient width for the trench that allows a mini excavator to be used, so about 1 m (39 inches) away from the fence. This also works better with the spacing of the manholes from the fence. Try not to place the manholes directly next to a fence post.

If the inspection shafts are only for your private use, a 45-degree T-piece and a vertical pipe section with a closure cap are sufficient.
It is important to have a slope of 1cm per 1m (0.4 inches per 3.3 feet) and to rarely (never) use the shortcut key.