Help with

Hello to all.
I have a small business network and have recently installed a RB951G-2HnD.
The problem i am facing is that when a user is downloading a big file or there is a PC updating windows it takes all the connection bandwidth and
until it finishes the rest of the network users cannot even browse websites.
How can i fix this?
Thank you.

Use the queues. There is a manual and tons of suggestions everywhere all around.

To be a little more specific, you should probably use PCQ

Don’t set any max-limit / limit-at / burst / etc… parameters in the PCQ type settings, a default behavior of “just divide it up evenly” is what you want here.
Then in the actual queue itself (with queue type set to pcq), set the max-limit to be your actually-available bandwidth.