If the number of concurrent connections to download an attachment has exceeded the default value set for your Symphony instance, a user may receive a Failed due to heavy traffic error message.
The default value is set to 50 connections per node; this value may be different depending on your Symphony instance.
For example, if an attachment is sent in a large room with 500 users, the first 50 users will be able to view the attachment immediately, but the 51st user viewing the attachment simultaneously will receive the Failed due to heavy traffic error message and a button will be displayed to them.
Depending on the size of the attachment, the user may have to wait a few milliseconds before selecting Retry to download the attachment.
In later versions of Symphony, a timeout between 1 to 20 is defined, meaning the user will no longer need to manually select Retry to download the attachment.