diff --git a/mods/default/player.lua b/mods/default/player.lua
index f7c34ab..35dc773 100644
--- a/mods/default/player.lua
+++ b/mods/default/player.lua
@@ -5,20 +5,66 @@
 -- Note: This is currently broken due to a bug in Irrlicht, leave at 0
 local animation_blend = 0
 local modelchar
-local eyeheithg
+local eyeheithg = 1.5 -- must be autodetected at client connection due different protocols
+local collsibox = {-0.3, 0.0, -0.3, 0.3, 1.7, 0.3}
 
 local is_50 = minetest.has_feature("object_use_texture_alpha") or nil
 
-if is_50 then
-	modelchar = "character50.b3d"
-	eyeheithg = 1.47
-else
-	modelchar = "character40.b3d"
-	eyeheithg = 1.625
+function dynamicmodel(player_name)
+
+	if not player_name then
+		if is_50 then
+			modelchar = "character50.b3d"
+			eyeheithg = 1.625
+		else
+			modelchar = "character40.b3d"
+			eyeheithg = 1.47
+		end
+		return
+	end
+
+	local engineold = is_50
+	local info = minetest.get_player_information(player_name)
+	-- ugly hack due mixed protocols:
+	if info then
+		local test = info.version_string or "5.0"
+		if test:find("0.4.") or test:find("4.0.")  or test:find("4.1.") then
+			engineold = true
+			modelchar = "character40.b3d"
+			eyeheithg = 1.47
+			collsibox = {-0.3, 0.0, -0.3, 0.3, 1.7, 0.3}
+		else
+			engineold = false
+			modelchar = "character50.b3d"
+			eyeheithg = 1.625
+			collsibox = {-0.3, 0.0, -0.3, 0.3, 1.7, 0.3}
+		end
+		-- only refix register model when protocols are mixed, will slow down server
+		if engineold == true and is_50 == true then
+			minetest.log("warning", "[default/player_api] performance impact: mixed protocols DETECTED on player .. "..player_name.." doin re-register model hack")
+			default.player_register_model( modelchar, {
+				animation_speed = 30,
+				textures = {"character.png", },
+				animations = {
+					-- Standard animations.
+					stand     = {x = 0,   y = 79},
+					lay       = {x = 162, y = 166},
+					walk      = {x = 168, y = 187},
+					mine      = {x = 189, y = 198},
+					walk_mine = {x = 200, y = 219},
+					sit       = {x = 81,  y = 160},
+				},
+				collisionbox = collsibox,
+				stepheight = 0.6,
+				eye_height = eyeheithg,
+			})
+		end
+	end
 end
 
 default.registered_player_models = { }
 
+dynamicmodel(nil)
 -- Local for speed.
 local models = default.registered_player_models
 
@@ -39,7 +85,7 @@ default.player_register_model( modelchar, {
 		walk_mine = { x=200, y=219, },
 		sit       = { x= 81, y=160, },
 	},
-	collisionbox = {-0.3, 0.0, -0.3, 0.3, 1.7, 0.3},
+	collisionbox = collsibox,
 	stepheight = 0.6,
 	eye_height = eyeheithg,
 })
@@ -83,7 +129,7 @@ function default.player_set_model(player, model_name)
 			textures = { "player.png", "player_back.png", },
 			visual = "upright_sprite",
 			visual_size = {x=1, y=2},
-			collisionbox = {-0.3, 0.0, -0.3, 0.3, 1.75, 0.3},
+			collisionbox = collsibox,
 			stepheight = 0.6,
 			eye_height = eyeheithg,
 		})
@@ -116,7 +162,9 @@ end
 
 -- Update appearance when the player joins
 minetest.register_on_joinplayer(function(player)
-	default.player_attached[player:get_player_name()] = false
+	local player_name = player:get_player_name()
+	dynamicmodel(player_name)
+	default.player_attached[player_name] = false
 	default.player_set_model(player, modelchar)
 	player:set_local_animation({x=0, y=79}, {x=168, y=187}, {x=189, y=198}, {x=200, y=219}, 30)