A question about ipv6

Hi guys, sorry to bug you with another question. But I use openVPN on Trisquel. When I check my IP on ipleak.net it will show my ip address on the right where it says ipv6. On my Windows PC, I disabled ipv6 and it fixed the issue. However, I'm not sure how to disable it on Trisquel. I found some commands on other forums, but when I did them it broke my internet connection and I had to reinstall Trisquel to fix it. I suppose it could be the servers I'm using, but it leaks my IP on ipv6 on all of them. Any idea how to fix this? Thanks for any help.