Leaving boat glitches you through blocks and makes you fall through nether tunnels

So, we have a nether highway in our server that has ice and we ride boats on top of it to travel super duper fast, but there is one problem, some of the roads are on top of lave and has no blocks below other than ice, and when we shift to get out of the boats on those kind of roads, we glitch and fall through the black and fall to the lava! We lose our items and stuff. Please fix this bug!