It has limitaion indeed. About 1000 for W8970 V1 as I know. Some others may support up to 3000.

The modem is connected to LAN4/WAN port and iMAC is connected to one of LAN ports, right? Normally, if you configure it as a wireless router and there is WAN IP address, it is done. What's the...

On its web interface, go to Access Management---UPnP and you can activate it. I didn't find AP isolation option on web interface of W8961ND. On Interface Setup---Wireless Page, change channel to 6...

Change MTU to1400. Any other wireless clients work OK by the router? Update the phone to latest version.

David, I don't think TP-LINK wireless routers has such a function to seperate wireless connection from wired connection in different gateways. Not sure if third-party firmware can do it.

Cannot control over 100Mbps since it is the maximum speed given by your ISP.