is there a network monitoriing program that can monitor my router's activity
 

is there a program that reports in real time (if possible) how many clients and which clients are connected to my router and how much bandwidth they are using from it. it would really be helpful to see how much bandwidth my router is transmitting (rating up to 300 Mbps but i want to know if it's transmitting to it's full capability) and it would be helpful to know how much bandwidth a client is using (i also ask for it to list the host names of the clients of possible along with their ip address) it's fine when displayed in verbose mode in the terminal with a list of clients and how much bandwidth their using because gui mode is too much for me for some reason i find some terminal programs more easier to use than GUI ones

SNMP
 

Not sure it's what you are looking for but it depends on the router. I monitor a lot of things on various equipment with Nagios. If your router supports SNMP you could use that or to try you could try the Dude from MikroTik. It has a good SNMP walk on it.

i'll try but i'm asking for a program that can tell me what clients are connected to the router and how much bandwidth their using, in real time

Like I said before, it all depends on the router, what it is capable of. What kind of router do you have? Does support any monitoring?

Wireshark may solve your problem

Try ntop. Run it on a monitor PC. You can either mirror your router port on your switch so the ntop machine can see everything, or if your router supports netflow exporting you can send netflow data to ntop over your IP network.

Ntop will then give you more kinds of analysis that you could possibly want about whos sending what where and how much.