Why do I connect to xbox live then disconnect

The IP address of your XBOX unit should fall within the subnet of you network. Use an ALL STATIC IP Addressing, this assures to have NO conflicts with other wired or wireless clients.

That said here we go:

Example:

1) R7000 IP address 192.168.0.1

2) XBOX IP Address 192.168.0.2

From the above example changing the last # "assigns" a SPECIFIC address, and no other client can use(DHCP, w/o IP reservation), in this case the XBOX. If you accidentally assign the same address, then you WILL have conflict. Always keep track of all your
clients address and this will not happen...write it down

HERE ARE THE PORT FORWARDING RULES BELOW

When you add port forwarding rules, please note that you can't use the same name XBOX 4times, router won't take it. Instead name each one like this:

1) XBOX 88

2) XBOX 3074

3) XBOX 53

4) XBOX 80

Below are the port forwarding rules:

If you have a firewall or network hardware, such as a router, you might need to make a configuration change in order for your PC or Xbox 360 console to communicate with Xbox Live. This configuration change is sometimes called “opening ports” or "port forwarding."

Xbox Live requires the following ports to be open:

Port 88 (UDP)

Port 3074 (UDP and TCP)

Port 53 (UDP and TCP)

Port 80 (TCP)

If you receive a NAT warning when connecting to Xbox Live, please see the Error: Your NAT type is set to strict (or moderate) page:

support.xbox.com/.../nat-error-solution

i normally connect to xbox live but something , there aren't problem in my connection but i don't know why i get disconnected a few of times for then be okay.

what is the problem?

No, it's not the same cable actually... but the same thing happens when using it wirelessly.

Just out of curiosity, what should I change in the router settings to make it wait more time before dropping a connection as a result of considering it dead (since there is no option to make the xbox keep the connection alive)?

Check this article related to the keep connection alive thing:
www.knowswhy.com/why-does-xbox-live-keep-disconnecting

ok im not getting any disconnections but now when i turn xbox on it says can not connect to xbox live. i have to do a internet connection test on xbox first then i can sign in . its like xbox isnt recognised untill i do test. annoying, but still i can play
. any suggestions why this is happening

iv tryed everything to disconnect my router and nothing factory defualt and turning off my xbox restarting it why cant i connect with xbox live