Did you change the wireless settings on the router, the WEP or WPA? When you enter the router's browser control program, can you see the wireless settings there and do you see wifi connected devices? What would the switch have to do with wifi anyway?
We have a small office setup and have a great need for the internet to work properly which it isn't doing right now. It is a somewhat complicated setup. Our ISP is Comcast and the modem and router are both updated and in the case of the router brand new. It is an Asus RT AC68p. The home previously had wired internet in multiple rooms which have now been connected to a new switch which is a D Link 16 port gigbit. Additionally there is a mother in law apartment with a separate router but connects of of our network. The two routers have different IP addresses so they do not conflict. One is set to 192.168.0.1 and the other to 192.168.1.1. When there was just a modem and the two routers with the old switch which only had 8 ports everything worked fine. I didn't have enough ports for all the wires in the house so I got a larger switch. Since I have added the larger switch the wireless is toast. Phones won't connect or say that they can't, laptops, and ipads won't connect either. We have windows 7 64 bit os on all computers. In network and sharing it shows an excellent connection and even says its connected to the wireless network but it either is turtle slow or drops it or disconnects and re connects randomly. I have scoured forums and tried many suggestions but nothing is helping with restoring wireless and keeping it. I tried going back to just the modem and the routers but the wireless still doesn't work. I didn't think a plug and play switch would cause this. I don't know what to do at this point to resolve this issue. The wired ports off of the router do work, but not the wireless. I can add whatever additional information is needed. Please help!