@alistairts Just an update on my situation. TP-link created a beta firmware update just for me to set my MTU at 1440. The update is working 100%, I only hope they release an official firmware update making this user configurable for all users to benefit. In a later issue, TP-link assisted me with another beta firmware update to fix the WAN auto-sensing port issue I experienced when I lose my internet connection. Basically, you lose the other LAN port when your internet connection is lost on the main unit. The provided beta firmware now sets the one port as permanently WAN, therefore the other LAN port remains functionable even without an internet connection. Thank you to Eva Liu and the TP-link support team!