Having read Codeit's post for Hub 3 router and routerguide.net, have made the following changes,
Block Fragmented IP Packets
Recommendation: Uncheck the box to disable this setting.
Although having fragmented IP packets supposedly tighten security more. Some connections such as you gaming consoles and media mobile devices do use fragmented IP packets. By enabling this option on, you can experience more connection losses and intermittent signals. So in general, turn the Block Fragmented IP packets off.
IP Flood Detection
Recommendation: Uncheck the box to disable this setting.
IP flood detection supposedly protect against denial of services type of attacks. However, turning on this option sometimes can hinder your wireless network speed in many cases. Some of your “real” traffic can be mislabeled and blocked by this firewall function.
You generally should disable IP flood detection. Unless you are having trouble with certain malware infected machines on a network flooding your entire wireless netork, but if that is the case, you really should try to get those devices fixed ASAP.
Port Scan Detection
Recommendation: Check the box to enable this setting.
In most cases as a normal non-tech user, you will not use any of the port scan features nor do you want to be found and be port scanned for open ports on your computer. Enable this function for the extra firewall security. Just turn this firewall option back on when you actually need to conduct port scanning.
Official description:
Detects and blocks port scan activity on both the WAN and LAN.
Source routerguide.net