Backup Central

We use Arcserve r12.5 SP1 (Build 5860) since the beginning of last week the average transfer fell from 1806.50 MB / min to 898.59 MB / min, and the amount of data remains the same.

When the copy is made where the server is not installed Arcserve the average transfer is 1806.50 MB / min, but when the file copy is made of the server where Arcserve is installed to the speed drops to 898.59 MB / min.

Can anyone help me understand and solve this problem.

Thanks.

run some tests to identify if the problem is only when backing up data from that target or only to the ARCserve server.
then at least you will have narrowed it down to one system to investigate
Windows Network Monitor and Performance Monitor can be helpful tools to use.
another thing to consider are conflicting applications as well as the number of jobs or processes running at the time.