Something like this has a pretty dramatic effect on the game, so I can understand your player balking. While it can add a level of realism and grittiness to a game, it makes combat significantly harder. Depending on which method you use, the number and/or difficulty of your combats will need to be dialed back, meaning rests will become more common, so your stories can't has as much of a time constraint.thank you all for all you input. it have given me a lot to think about. just talked to 1 of my players he told me he will not play any more if i make a house rule that only will affect the players. and he is correct on this 98 - 99 % of the time this house rule will only affect the player. so a lot to think about
While I personally not a fan of the "tubthumping" effect 5E combat can have, the only aspect I've felt any need to change is to make the 20 success on a Death Save simply stabilize you, rather than grant 1 HP. If the players try to meta-game healing by only using it on downed characters, start using enemies with AoE effects that will grant another failed death save to those characters, putting pressure on the healers to act quickly before 3 death saves.