So there I was, trying to jump on a friend's Minecraft server on a Friday night, and I kept hitting that same stupid screen — "Failed to connect to the server. Connection refused: no further information." Meanwhile my friend is telling me the server's fine, everyone else is on it, and I'm just sitting there refreshing like an idiot. Sound familiar?
The "failed to connect to server" error in Minecraft is one of those issues that looks simple but can be caused by about six different things at once. I've seen it on Java Edition, Bedrock, self-hosted servers, and third-party ones like Aternos. The error usually looks something like this in your game:
Failed to connect to the server
java.net.ConnectException: Connection refused: no further information
Or sometimes the more vague version:
io.netty.channel.AbstractChannel$AnnotatedConnectException:
Connection refused: [server IP]:25565
That port number — 25565 — is almost always relevant. Keep it in mind.
Why This Actually Happens
Here's the thing though, this error rarely means the server itself is broken. Nine times out of ten it's a network issue on your end, a firewall being overprotective, a stale DNS cache, or — and this one gets people all the time — Java version mismatches. If you're on a cracked or modded client, you've got even more variables to deal with.
Sometimes it's also just that the server is genuinely down or starting up (Aternos servers go to sleep and need a minute to wake up). Before you go deep into troubleshooting, give it 60 seconds and try again. Seriously. I've wasted 20 minutes diagnosing a server that just needed to boot.
Alright, assuming it's still broken — here's what to do.
Fix 1: Flush Your DNS Cache
This is the first thing I try every single time. Your system caches DNS lookups, and sometimes that cached record goes stale or gets corrupted, especially if the server IP recently changed. A quick flush sorts it out.
On Windows, open Command Prompt as Administrator and run:
ipconfig /flushdns
ipconfig /release
ipconfig /renew
On macOS:
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
On Linux (Ubuntu/Debian):
sudo systemd-resolve --flush-caches
After that, try connecting again. Honestly, this fixes it about 30% of the time on its own. It's annoying how often something this simple works.
Fix 2: Check Windows Firewall (or Your Antivirus)
Windows Firewall and third-party antivirus tools love blocking Minecraft, especially after an update. Java Edition in particular triggers firewall prompts sometimes, and if you accidentally hit "Block" once, that setting sticks around forever until you manually fix it.
You can quickly check this by temporarily disabling your firewall and seeing if Minecraft connects. If it does — there's your culprit. Don't leave it disabled, though. Go add a proper exception instead.
To add Minecraft's Java executable as a firewall exception via PowerShell (run as Admin):
New-NetFirewallRule -DisplayName "Minecraft Java" -Direction Inbound -Program "C:\Program Files (x86)\Minecraft Launcher\runtime\java-runtime-gamma\windows-x64\java-runtime-gamma\bin\javaw.exe" -Action Allow
The path might be slightly different depending on your launcher version — just browse to it manually in Windows Defender Firewall if the command doesn't work. Also worth checking: if you're running the server yourself, make sure port 25565 is open on your router for TCP traffic. That's the default Minecraft server port, and routers block it by default.
Fix 3: Check Java Version and Game Version Mismatch
This one's sneaky. If you recently updated Minecraft and your server is running an older version (or vice versa), you'll get connection errors that look exactly like a network problem but aren't.
In your Minecraft launcher, you can force a specific version by editing your profile. In the official launcher, go to Installations → Create New → Version and pick the one that matches the server.
If you're running a server yourself, check what version it's on by looking at your server.properties file or just checking the console output when it starts:
[Server] Starting minecraft server version 1.20.4
Match your client to that version and try again. This is especially common when people run modpacks — if the server is on Forge 1.20.1 and you're trying to join with a vanilla 1.20.4 client, it's just not going to work no matter how much you troubleshoot the network.
Fallback: Switch to Google's DNS
If nothing above worked, try switching your DNS server to Google's public DNS (8.8.8.8 / 8.8.4.4) or Cloudflare's (1.1.1.1). ISP-provided DNS servers can sometimes cause weird resolution issues with game servers, particularly ones hosted on dynamic IPs or services like playit.gg.
On Windows, go to Network Settings → Change Adapter Options → IPv4 Properties and manually set your DNS to:
Preferred DNS: 8.8.8.8
Alternate DNS: 8.8.4.4
In my experience, this also helps with general internet weirdness beyond just Minecraft, so it's a decent change to make anyway.
One last thing — if you're on Aternos specifically and getting a "failed to verify username" type error alongside connection issues, that's a separate beast tied to Mojang's authentication servers. Try logging out of the Minecraft launcher completely, logging back in, and then connecting. That session token expires sometimes and causes all kinds of confusing error messages.
Hope this saves you from a wasted Friday night. Start with the DNS flush, work your way down — most people don't need to go past Fix 2.
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