Create a button in sharepoint Online

I have seen your previous conversations about these issues you are experiencing.  They may not be a general issue by the sound of it and I think you have to push Microsoft support for a resolution and also be responsive for any troubleshooting steps they may require.  

As you have been advised already, to check your network quality, which is worth ruling out as a possible cause too.  I think most of us would guess it’s network related, that would explain the intermittent nature of the issue but since Office 365 support seemingly mentioning SharePoint servers as a possible cause that needs some explaining too. I’d be asking them for updates, probably twice a day, if it is a problem at their end and some sort of escalation at this point.

Good luck!