CooP Host Constantly Disconnecting on Steam

[viscid valley]

my SO is hosting the game. Every couple of minutes, ranging from 3 to 60, the game gets disconnected from the server. A couple of seconds later, I see their Steam "now playing Coral island" pop up again, so it also disconnects Steam, at which point it says that I lost connection.

Why do i suspect Coral Island to be the culprit and not network/firewall/steam? All other games, regardless of whether I or they host, are rock solid, steam never disconnects, and we generally have a very stable internet with barely any problems ever. Also, we both work in IT/Cybersecurity, so we can rule out most Firewall, Router and similar networking issues unless they are extreme edge cases

I don't know if it helps, they're running bog standard windows 11, no mods, no fancy antivirus like Norton which has caused problems in the past or anything else

-Most current steam game version, so v1.2b-1246

here's the save file, if you need any other info I'll provide as needed

[cerulean shore]

Can you try and sync time on the PC, it helps with most connection issues
-# not a dev

[distant bramble]

Hi there @viscid valley , So sorry to hear you’re running into connection issues during Co-Op—we totally get how frustrating it is to lose progress because of it 😞

Could you let us know when the issue started happening? Also, would you mind sharing the error message that both the Host and Guest see after the disconnection? Thanks a lot!

[viscid valley]

I'm not sure what you mean with when it started happening:

• We got the game on march 8th 2026, and it's been happening on and off since then whenever we play, the latest occurence being yesterday, march 29th. Sometimes we can play for a couple of hours now, sometimes it disconnects within a minute of hosting the world.
• If you mean in-game when/event wise, since day 3 I guess? I couldn't tell you of a specific event or ocurrence in-game after which it ocurred.
• We mostly play after work in the evening, that being UTC+2, 18:00 to 22:00 if it's a server load issue

i left the game running all day today in the background to get the exact error message for a screenshot, but of course it's been running flawlessly all day, thanks murphy. I'll send a screenshot as soon as i have a disconnection.

Thanks for taking the time with all of the bug reports and feedback

[distant bramble]

Well noted, thanks for providing us with some additional information! Could you try syncing the time on your PC? Some players were able to resolve the issue this way!

You can do it by going to:

• Start, then Settings, then Time & Language, then Date & Time
• Make sure “Set time automatically” is turned on, then click “Sync now.”

Let us know if this works for you! 😉

[viscid valley]

I tried the steps, even before that it was a lot less frequent recently, but the disconnect ocurred again. I sent the screenshots of the host and joiner (named as such)

[cerulean shore]

Not a dev, but a question. Did both of you sync time? And if so, can you screenshot the time settings page and send it over here.
Or try syncing via steps again. Most connection issues with PC are solved that way.

And you also mentioned that the game didn’t disconnect when you left it open. Does the game disconnect when you play alone or only when the guest joins?

[lost raptor]

Another player in our community mentioned they were able to fix this issue by syncing their system timezone.
You could try the steps below to see if it helps:

• Select Start, then go to Settings > Time & Language > Date & Time
• Make sure “Set time automatically” is turned on
• Then click “Sync now” under the Synchronize your clock section

Could you let us know if this solution works on your end?