Having bandwidth issues on xbox?

I'm not really sure how to phrase this since I am not the biggest tech guy but recently I have been having issues with my bandwidth on xbox. I am having issues not lagging in games and it only recently started to happen, I checked and even though I have three computers running on the same connection as my xbox I never had issues before, but to make sure it wasn't the issue i unplugged all computers from the router turned off the wireless connection and plugged my xbox directly into the router and I am still having issues with bandwidth, ( so both the wireless connection and my wired connection for xbox is having issues). So what it boils down to is could port forwarding for my xbox increase bandwidth and if not do you have any ideas cause I have even tried changing the broadcast channel for my router in-case another router was interfering with connection. Thanks to whoever replies.