@OutdoorsTB,
We haven't really ever seen requests to change the MTU size for Deco in the past, however we have been seeing the request more often over the last few months. In fact, in the latest firmware released last Friday, the Deco X50 and Deco X55 were updated to allow changing the MTU size. As this is the first time we have seen this added as a feature to the deco lineup, it may take some time to develop the feature for other/older models, but the feature is being worked on for deco.
I am adding MTU packet size customization to our list of suggestions to our development team so they understand that the feature is welcomed for more deco models and transferring your post to our feature requests so that other users can express their interest in the settings.
I am curious about how often you experience issues with the MTU size and what you are seeing that indicates that this is the root cause. While I know what can happen, I feel like the effect of MTU size is not commonly seen at a residential/consumer level.