mzez wrote

So I would try to renew lease with the iphone, but it would constantly return back 169.254.xxx.xxx.

169.254.0.0/16 are IPs reserved for use by ZeroConf. If your device sets an IP from this IP range, then either the DHCP server isn't running or the DHCP address pool has been exhausted. Check your DHCP settings on the Hitron router.

Would setting up static IP/DNS for all the devices look like a good solution for my issue?

Not for all devices. But for stationary devices such as EAPs, servers, switches and immovable PCs you should prefer static IPs, while for mobile devices you should assign IPs dynamically using DHCP.

Note that in small networks/home networks you can use static MAC-to-IP mappings in the DHCP server to achieve a static IP for a stationary device. To be precise, it is actually not a static IP, but a fixed IP reserved in the DHCP sever for a specific device identified by its MAC address. Such fixed IPs do not need to be taken from the DHCP server's pool of dynamic IP addresses.

This method to set a fixed IP has two advantages over setting a static IP on the device itself (e.g. using ipconfig on a PC): first, you can manage fixed IPs in a central place on your router and secondly you can assign this fixed IP a DNS name on most routers, so you can reach the device by name in addition to its IP. The disadvantage is that you still use the DHCP protocol to set a fixed (»static«) IP.

Again, see the DHCP settings in your Hitron router and look for MAC/IP mappings in the DHCP section.

Dear @mzez,

Hello everyone, I purchased a EAP225 and tried installing it today, all seemed to work well and I connected my main computer to the EAP225 fine and had internet. 

What IP address is obtained on your main computer for accessing the Internet?

If the IP address is public, then you need a router to share the Internet with other devices. As @JSchnee21 mentioned, the EAP225 is just a wireless access point, it cannot work as a router. Please set your CGN3 Hitron modem/router as Router mode, then the other devices should be able to connect to Internet. If you don't know how to do it, it's suggested to contact your Hitron support for assistance.

Bebe1980 wrote

However the TPLink router also has ARP binding... MAC to IP - When would you use that?

You would use that to mitigate against ARP cheating / ARP spoofing attacks. See this recent thread why such a mitigation can be useful.

As for naming devices in MAC-to-IP mappings it can be done in almost all devices which use either dnsmasq or ISC DHCP as the DHCP server, that's for example all OpenWrt-based routers.