Outlook for Mac lose connection intermittently

[Daniel_Sun]

We are using Exchange  2016 CU 20, some mac user report that outlook loses connection intermittently, and auto fixed in few minutes. From IIS log, there is some http 500 error. but still have no idea how to fix

[#2]

have you tried repairing office, or reinstalling it? Can the user use Outlook on the Web as a work-around? Are other macOS users reporting this same problem, or is it isolated to this one user? Did the problem just start happening after installing CU20 or has it always happened?

[#3]

@Joe Stocker 

Multiple users reported the issue. And the issue already occurred when we are running CU18.

I don't think using owa is a good solution. Many VIP users use macbook.

[#4]

There are a lot of things this could be: the internet service provider could be dropping packets. If Exchange is virtualized, it could be a problem with the network stack/drivers or even over utilization of bandwidth at any point of the network segment.
Can you post the IIS 500 Error?