Even if you know it's symmetrical it has several solutions.

It is totally symmetrical and I found only one solution. Nice pic thanks.

IF you admite the picture is symmetrical, there is "only" 12 solutions. Indeed, there are 6 solutions in the area R3-5C9-12 (and its symmetric), and there are 2 solutions in the area R15-16C11-12 (and its symmetrical) which are independent. In addition, symmetry is unfortunately not a proof of logic.
It's a shame because the picture is beautiful.

Worked perfectly for me. Thanks Nicanners. Only one solution.

Multiple possible solutions, but easy enough to guess. Nice image. Thank you!