Client systems cannot open Enterprise 2024 company if server has already opened it

Thanks for reaching out to the Community, iragrollman. I appreciate your detailed information and screenshot.
 

Since you've performed most of the recommended troubleshooting for the "Cannot communicate with company file" message you're encountering, I'd recommend confirming you meet each of your product's system requirements.
 

One thing I've noticed is that you're using Windows Server 2025. This specific server is currently unsupported for use with QuickBooks Desktop Enterprise 2024.
 

For database servers, you must use a natively installed version of Windows.
 

Here are the required and supported Windows servers for QuickBooks Desktop Enterprise 2024:
 

• Windows Server 2022, Standard and Essentials
• Windows Server 2019, Standard and Essentials
• Windows Server 2016, Standard and Essentials

You'll want to switch to using one of these required servers. If you continue using an unsupported Windows Server, like Windows Server 2025, your product may not function as expected.
 

Once you've switched to a supported server, you can repeat your normal processes and see if the same "Cannot communicate with company file" message continues displaying or not.

I'd also recommend reviewing each of your product's system requirements to confirm you meet all of them. This will ensure you aren't encountering unexpected behaviors while using your product. You'll be able to find them in our System requirements for QuickBooks Desktop 2024 article.

Please feel welcome to send a reply if there's any questions. Have a wonderful Friday!

@iragrollman 

Open the sample file in multiuser mode. Did you encounter the same problem?

I posted about lack of Windows server 2025 support in another post. Windows Server 2022 goes EOL shortly and the other supported version of Windows Server are already EOL. Enterprise 2023 was working fine on Windows Server 2025, but the Intuit messaging about ending support for 2023 caused the client to attempt moving to Enterprise 2024. Windows 11 does not run properly on server class systems that have the performance for Enterprise customers.

I posted about lack of Windows server 2025 support in another post. Windows Server 2022 goes EOL shortly and the other supported version of Windows Server are already EOL. Enterprise 2023 was working fine on Windows Server 2025, but the Intuit messaging about ending support for 2023 caused the client to attempt moving to Enterprise 2024. Windows 11 does not run properly on server class systems that have the performance for Enterprise customers.