Siphon ATLANT does not hold

Hej,

two months ago we had the Boholmen sink connected with the siphon Atlant by a plumber. Today, while washing up, we suddenly hear a splashing sound coming from the cabinet below and lo and behold: the siphon is hanging in the air and water is draining in all directions.

Now we wonder how the siphon ever stayed attached to the sink. There is no visible fastening option. The screw in the drain is not a screw but a metal rod without threads. Question: How can we secure the siphon again?

Thanks in advance!
S.

After thorough troubleshooting, we found that there actually was a thread. Unfortunately, it broke and got stuck in the corresponding guide in the siphon. The plumber did not think to install a relieving attachment for the entire siphon, so the entire siphon with hoses was only hanging on that one screw. Of course, this cannot work in the long run.