You set it in the delivery method under Network Usage- Multicast Limits - Maximum Number of multicast domain representatives working simultaneously
The Default of 5 refers to the maximum Number of Multicast Domain Reps working at the same time not clients. There will be one Domain Rep per broadcast domain(usually subnet).
Clients are set to default to 61.
When you 1st open the delivery method window on the description section you will see a box thats states Number of Devices for simultaneous distribution this fields controls the maximum number of devices that can simultaneously receive the software distribution.
With that being said I have not seen a reason to have more than 61 devices working at the same time all though there might be a few out there. All that means is machines are processed in batches of 61.
To clarify, the 61 refers to the number of machines installing at any one time, all target machines on each subnet will receive the package simultaneously via multicast regardless of the 61 setting. This setting just means that up to 61 will be sent the command to install the package and be monitored for progress.
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