Hello. having a bit of an issue. I have a wireless network with about 150 people all coming to my main office via backhauls. In my main office I have 15 meg fiber into a 2ghz mikrotik with 3com cards for my main router. After that the line goes into a linksys sr216 switch which has my internal router off of it as well as one server and all of the wireless clients. When I do speed tests with everything plugged in I only get about 5 meg down and about 7 meg up. However if I just unplug 1 wire going to my wireless backbone out of the switch, my speeds jump to 14-15 meg. Now the obvious is not there, the wireless clients are not using anywhere near 15 meg. So there should be plenty of line left with everything plugged in. Is there anything that could cause this sort of thing? maybe a problem with a switch or the mikrotik? Thanks in advance…
you said - that everything plugged = 5 MBit up/down
you have available 15MBit
you have 150 wireless clients
so, clients get arond 100KBit/s each
that nuber is ok if they do just webbrowsing, e-mails, some casual downloads.
IMHO it is good, that there is 5MBit/s left for you to use. 
or you ment 15MB (Bytes)/s ?
When i monitor my line usage it is only at like 4 meg max. Also when i am lookign at the switch and plug in the main backhaul cable the light for it, and the main line turn completely solid usage. seems like a storm.
could yo have some bridging there? and thats maybe is creating loop, try rstp or stp if this is the case
Could this be " Collision " issues ?,
150 clients/nodes talking to eachother on same network segment could create a lot of talking to eachother i think ?
was searching forums, white papers etc to learn some more how to detect/prevent collision issues , maybe someone with more then 150 users can tell us some good pointers…