This is so called Tavern puzzle or disentanglement puzzle. I have a huge collection of them and enjoy solving them and watching others suffering to solve them. This one is medium level difficulty. It has a name called Cowboy's Hobble.
Eventually, the most difficult one Freedom's Ring from Tavern Puzzle has the same pattern as Cowboy's Hobble. So, if one could resolve Cowboy's Hobble, he can resolve Freedom's Ring in no time.