Network problem on W7 computers

My spouse and I are connected directly to the router. Our son connects wirelessly. Everything use to be fine and not sure what happened, but now when our son connects to my computer it causes me to lose the ability to see others on the network. Our son even said when he was trying to download things from my computer, it was really slow. (One file..250m..used to take about 5-10 minutes..now takes an hour or more.)
Since I access my spouses computer several times during the day, it was necessary for him to reboot, then I could see him again.
So we tried having my son connect to my spouses computer, but that didn’t work because then my husband couldn’t see anyone on the network.
I hope this is not too confusing because I have tried several things to find out why this is happening, but everything seems to be in order.
I would appreciate any ideas, maybe even a solution if someone else has had this happen to them.
Thank you to anyone who can offer an idea of what is happening.
Answer #1
You can try to reset router.
Answer #2
I will try. Thank you for responding.
Answer #3
Here`s another idea
You could always change the channel of your router,to do so you have to login to it using a specific ip (depends on the router model).username/password should be admin/1234 it does specify though when you access the ip.
You should see a page with varios settings,look for wireless settings,i think it`s under basic,you should see something like this aprox

be advised changing the channel may cause some devices to not see the router at all,change the channel number untill all devices can see the router
i found my router ip by googling btw
EDIT
list of ips/models/how to find ip via windows
http://www.techspot.com/guides/287-default-router-ip-addresses/
Hope it helps
Answer #4
You can install Ftp server [filezilla server] on all pc.
http://www.howtogeek.com/140352/how-to-host-an-ftp-server-on-windows-with-filezilla/
Answer #5
Wow, thank you guys for all this info. I will be trying these ideas soon.
Thanks again.