Singleplayer worlds don't work [with disabled ipv6 in system]

[rudzik8]

Minetest version

freeminer 5.8.0.0-dev-fefbb53 (Linux)
Using Irrlicht 1.9.0mt13
Using LuaJIT 2.1.0-beta3
BUILD_TYPE=RelWithDebInfo
RUN_IN_PLACE=1
USE_CURL=1
USE_GETTEXT=1
USE_SOUND=1
STATIC_SHAREDIR="."
STATIC_LOCALEDIR="locale"
ENABLE_THREADS
USE_MULTI
USE_ENET
USE_WEBSOCKET
MINETEST_PROTO
MINETEST_TRANSPORT
USE_TRANSPORT="multi";

Active renderer

OpenGL 4.6.0

Irrlicht device

X11

Operating system and version

Linux Mint 21.3

CPU model

No response

GPU model

No response

OpenGL version

No response

Summary

Whenever I try to connect to a new singleplayer world (no matter the game, no matter the mods), I get this:

2024-05-10 16:02:42: ACTION[Main]: freeminer v5.8.0.0-dev-fefbb53 	 threads 	 multi: 	 mt 37-43	 enet 	 ws 	 cpp=202002 	 cores=4
2024-05-10 16:02:42: ACTION[Main]: World at [/home/rudzik8/freeminer/_build/../worlds/5555]
2024-05-10 16:02:42: ACTION[Main]: Server for gameid="Repixture" mapgen="singlenode" listening on [::1]:55624.
2024-05-10 16:02:42: ACTION[Env]: [rp_weather] Weather set to: clear
2024-05-10 16:02:42: ACTION[Main]: Multi connect to ::1:55824 with enet
2024-05-10 16:02:42: ERROR[Connection]: connect enet_host_service ret=-1 event.type=0
2024-05-10 16:02:42: ERROR[Main]: Connection error: Failed to connect
2024-05-10 16:02:42: ACTION[Main]: Server: Shutting down

Steps to reproduce

1. Create a new world
2. Ensure that Host Server isn't checked (so it's a singleplayer session)
3. Try joining it

[proller]

Try build with -DUSE_MULTI=0

[rudzik8]

Try build with -DUSE_MULTI=0

It doesn't give that error now, but the connection just times out.

2024-05-11 09:17:00: ERROR[Main]: Access denied. Reason: Connection timed out.

[proller]

do you have enabled ipv6 ?

try disable in config:

enable_ipv6=0
ipv6_server=0

[rudzik8]

do you have enabled ipv6 ?

try disable in config:

enable_ipv6=0
ipv6_server=0

This did help, but singleplayer is extremely laggy for some reason (not in terms of FPS, but in terms of actual delay between, for example, you breaking a block and it actually disappearing, or you picking up a dropped item). But that's for a different issue.

It would be nice though if this worked without modifying the config, which is why I'm not closing this.