An easy fix to this would be to tick the option Plugins -> FFXIV Settings -> Disable Parsing from Network Data (Note: this means you won't be able to upload parses to FFLOGS.COM). When you're using ACT parser to parse damage numbers, the numbers turn out all wrong and inflated if you're using Mudfish with FastConnect mode enabled. As long as you don't fully close down the game you can easily get right back into the it with (hopefully) much better performance provided you've shared the mudfish adapter again.
Just wanted to give the tidbit to anyone seeking answers (if these messages can be seen by others) if you first login to FFXIV on PS4 using your normal internet, shared or otherwise and then share the mudfish (tap driver) once you're on the Stormblood title screen you can actually get mudfish to work with the game without full vpn mode which is great as it means only FFXIV will go through mudfish.
Please check FAQ - Nodes link to know how to pick a better node. Specify mudfish node you'd like to use rather than "Auto Selection" for picking a node. This mode is available after Mudfish Cloud VPN v5.4.2. If you want to avoid this issue, please try to use WFP Item mode. Sometimes this game item causes CDN and Mudfish issue and affects your browser's traffic. To play Final Fantasy XIV - A Realm Reborn with mudfish, these are useful tips here.