Yes, absolutely, turn it on. If this is implemented correctly your firewall's engine should inspect each packet. Once it's determined to drop this traffic as part of a DoS attack, it should install a rule into hardware and silently drop the traffic instead of processing it again and again.

Should I disable DoS protection?

However, some people select the “disable port scan and DoS protection” on the WAN screen; the protection will be disabled. But we suggest that you always enable DoS protection because it not only saves the network but offers protection to your devices as well.

Does DoS protection slow router?

The Disable Port Scan and DoS Protection feature can be enabled or disabled in the NETGEAR router GUI. ... This causes a Denial of Service (DoS) and results in slow access to the Internet, since the amount of traffic attempting to ping your IP address overloads the router.