cannot travel, place, or remove blocks on 1.12.1

When trying to do any travel I can make it 5 blocks forward then get shot back 6 blocks so im just effectively running in place. When clearing I have to break the same block 10-15 times and placing blocks just disappear only to reappear to stick me in the block and suffocate me and/or blocking any movement. This is the same for the 5 other people on the server be it playing together or alone on the server it makes no difference. we've tried all the trouble shooting and even at a render distance at 2 the games core mechanics are near unusable.