The WiFi stability on the TPMC's can be horrible and the range is stated at about 30' given the best environments. A ship is not one of those best environments. How is your wifi network setup? Do you have dedicated WAP's for each 8X? Are the WAP's for the control system on a separate VLAN from the other networks? Have you tried shorter SSID and turning security off for the problematic 8X's? What brand and model WAP's and how far are they from the 8X's intended area of usage? What firmware version are you running on the 8X? And last but not least what WiFi standard are the WAP's on?

If you have a system that large on a ship that was only 500k it sounds like you may have been undersold on the network side of things. That's a huge system and the network alone could easily be in the high 5 to 6 figure range.