@SupremeGunman You can set all static IP addresses out of the DHCP range, thus you can completely avoid IP conflict. This should not affect your internet connection.

@Lasermatrix You don't need multiple controllers. One controller can manage devices across the internet. See this FAQ: https://www.tp-link.com/us/support/faq/2763/

@WesRehn What's the link speed between two APs? Is the link speed normal?

@chiptransisto Try MAC clone. Cloning the MAC address if the laptop to the WAN2 interface. If it still doesn't work, you need to check the physical issue. When you plug the modem into WAN2, does the...

@rtinsky Yes, but you need to upgrade its firmware to the latest one(1.1.1): https://www.tp-link.com/en/support/download/er605/#Firmware

@H7FM You should set the allow rule in front, and then the deny rule. ACL rules will take effect in turn from top to bottom.