Pretty much any time i try to launch No Man's Sky, when it tries to sync the save games, it will sit there for about ten seconds trying to contact the server, and fail. Same thing when exiting the game. Maybe one time in thirty it says it successfully synced the saves. This has been going on for months for me.

I have looked into stuff like bypassing my software and hardware firewalls, as well as using a VPN, to no avail. Same problem on Windows 7 x64 and Windows 10 x64. Galaxy itself has no problem connecting to the internet, both for browsing the store and downloading games/updates. Other games work with Galaxy cloud saves just fine, like RiME and Nex Machina. No Man's Sky itself has no problems accessing its servers for uploading discoveries etc. I always keep the game up to date on the regular channel, not the experimental/beta channel.

Also, when I try to play the game on my second computer, it will see the newer saves in the cloud, but when I download them, it will only have synced one of my save slots. It will also say "Cloud saves not synced" after closing the game on that computer as well. Now, the last time I tried to play on the other computer, the save I synced from the cloud (which sucessfully synced from my main computer only two days prior) must have been corrupted, because when I loaded it, it started a brand new game.

I have not gotten a hit on this issue with a google search. The closest I've gotten was some posts on the GOG forums for Stardew Valley and The Witcher 3. Is it really just me?

Occasionally, but very rarely, I'll have a problem syncing. It seems to correlate to times shortly after booting the PC when all of the background stuff which Must Occur RIGHT NOW (apparently ;-) is slurping up disk I/O, CPU cycles, and network bandwidth.

Most of the time, though, syncing Just Works. The packets seem to be pretty small and syncing in either direction takes just a few seconds.

I'd suggest firing up Resource Monitor and holding off launching NMS until the post-boot processes have settled down. You can also (at least on 7; not sure about 10) do a [Window's key]-D to bring up the desktop when you're ready to exit and check Resource Monitor to see what competing processes are running.

AFAIK, firewalls shouldn't be an issue. Perhaps an antvirus app is holding up the sync to do a "reputation verification?"

I often don't start the game until my computer has already been on for a while (several hours.) My OS drive is an SSD and rarely ever bottlenecks the system.

Thanks for the tip on disabling my antivirus/antimalware stuff to see if that would help, for some reason I forgot about that. Unfortunately, it didn't make any difference. On Windows 7, I have Avast free for antivirus and Comodo Firewall free. On Windows 10, I am using Windows Defender for antivirus, Malwarebytes Premium for antimalware, and Windows Firewall (I had issues with both Avast and Comodo randomly disabling on Win10).

It certainly isn't the end of the world if cloud saves don't work for me. It does look like the problem is something with my setup, rather than an issue with Galaxy + NMS, otherwise I would have more "Help Me!" repies :-)

One thing which I can't explain that may relate to your problem is that I have noticed that when the machine has been up for a while, I do sometimes have problems launching NMS. I don't have enough samples to establish causality since I usually don't boot the "game box" and let it sit there but it's annoying enough when it does happen to be noticable.

Problem is, of course, that it's hard to think of a mechanism that would account for either issue: cloud saves or balky launches. A memory leak would be my first thought but GOG and Galaxy don't show up in the list of running tasks or services prior to launch so <shrug>.

Do you get the same problem after a clean reboot?

Win7 Pro 64, SSD C drive, with Malwarebytes Premium and Avast Internet Security. Games, insofar as I can coerce them, are installed to a regular spinning disk.

Yes. Same problem after a clean reboot on both operating systems and both computers (I dual boot Win7 and Win10 on my main system, my second system is just Win10.)

I also install my games on a mechanical hard drive as well. I actually got a Seagate 10gb Helium Enterprise drive a few months ago so that I could fit my rather large Steam library and growing GOG library on one drive. It's awesome!

Well, I couldn't say what changed, but it suddenly works now. As far as I know, I'm not doing anything different.

"Well, I couldn't say what changed, but it [(suddenly works) | (quit working)] now. As far as I know, I'm not doing anything different," pretty much describes using anything on MS WIndows. ;-)