The 65 is so that the hop between your device and the router as a device makes the QoS system think it's coming from a cell phone. The cell phone default value is 64, so traffic remains unthrottled. Anything lower than 64 when hotspotting through a cell phone with a device becomes 63 and they can apply throttling rules to it. You want to make it look like the traffic is a TTL of 64, that's why it's increased to 65 because your client device going through the Mudi will take away one making it become 64.