Your Trados GroupShare Server is intermittently unavailable.
In the Windows application logs of the web server you find following error:
 

WebHost failed to process a request.
Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/41149443
Exception: System.ServiceModel.ServiceActivationException: The service '/Platform/sdl/discovery.svc' cannot be activated due to an exception during compilation. 
The exception message is: 
Memory gates checking failed because the free memory (x bytes) is less than 5% of total memory.
As a result, the service will not be available for incoming requests. To resolve this, either reduce the load on the machine or adjust the value of 
minFreeMemoryPercentageToActivateService 
on the serviceHostingEnvironment config element.
at System.ServiceModel.Activation.ServiceMemoryGates.Check(Int32 minFreeMemoryPercentage, Boolean throwOnLowMemory, UInt64& availableMemoryBytes)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CheckMemoryCloseIdleServices(EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
--- End of inner exception stack trace ---
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath, "

 

The error above indicates memory pressure on the machine where the the web server is installed.

Solution: Resolve RAM Bottleneck

To resolve the problem, solve the RAM issue.

Note: If SQL Server (non Express Edition) is installed on the same machine as the web server, SQL Server is likely to consume large parts of the memory, which may cause above error.
In this case, consider reducing the Maximum Server Memory option to a value that reserves enough memory for all other applications on the server but is still high enough to ensure satisfactory performance of the SQL instance. See this MSDN article about SQL memory options.

Workaround: Disable Memory check

As a workaround, you can use the approach explained in the error message and this MSDN article.
These steps have to be applied to the web.config file found at C:\Program Files (x86)\SDL\SDL Server\Web\Platform.
Please

The Web Server service by default does not activate for new requests if less than 5% of total RAM is still available to ensure system stability.