Your request for help is not written very clearly. You might want to provide more details about what you are doing if you want to find the answer to your problem.
You mention wget in the title but not in the body of your post. Is the problem occurring only with wget? What about the firefox download manager? What do you mean by 'my server" ...
The download rate for retrieval by wget is capped by adding a limit rate, as per the following example:
wget --limit-rate=20k http://www.downloadexample.com/file.tar.gz
This will limit the retrieval rate to 20KB/s.
If you do not specify a limit, then the download will be retrieved at the maximum possible speed.
Learn how to use wget by studying the man page. wget is a wonderful powerful tool.