I make my own cables from 4mm single core fibre optic, link below but I bought 15m and so had a quite a bit left to test with. In fact, it triggered my strobes over a 10m length. Source was an Olympus EM-5 with accessory flash (FL-LM2) to a Inon Z-240. I won't use that sort of length but the cable works really well.
https://www.ebay.co.uk/itm/223205400644?var=522004584178
"Fibre optic lighting cable in 3 mm / 4 mm black PVC waterproof tube (DIY)"
I use the "Sourcingmap 20pcs 27mmx7mmx4mm Micro Strain Relief Cord Boot Protector" and "sourcingmap Fluorine Rubber O-Rings, 7mm OD 5mm ID 1mm Width FKM Seal Gasket for Machinery Plumbing, Green, Pack of 50" off Amazon to make the connectors..