Unfortunately, it's one of the main limitations of External List!

If the number of retrieving items is more than 2000 items, the external list will not working properly. you will face a performance issue and it may be stuck to render!

Fortunately, you can exceed the default max limit (2.000 items) using Set-SPBusinessDataCatalogThrottleConfig cmdllet to the absolute max (25.000 items).

But unfortunately, exceeding the default max size is not recommended based on Microsoft support response. Moreover, the performance issue will not be solved  !!

For more details check THE EXTERNAL LIST LIMITATIONS IN SHAREPOINT 2013 /2010

Unfortunately, it's one of the main limitations of SharePoint External List!

In External List, If the number of retrieving items is more than 2000 items, the external list will not working properly. you will face a performance issue and it may be stuck to render!

Fortunately, you can exceed the default max limit (2.000 items) using Set-SPBusinessDataCatalogThrottleConfig cmdllet to the absolute max (25.000 items).

But unfortunately, exceeding the default max size is not recommended based on Microsoft support response. Moreover, the performance issue will not be solved!!

For more details check

• SharePoint 2013 BCS Service Application Throttle Management
• The external list limitations in SharePoint 2013 /2010