A couple of the staff that go to events around the world like the Super League Arena Games responded.
There are several areas of concern, as you’re aware. The major concern is to reduce radio frequency (RF) interference, to the degree that some things are out of your control.
Wireless link between trainer <> computer running Zwift
If the computers have a USB-A port, it’s strongly recommended you use ANT+ dongle on a USB extension cable. Place that dongle as close as possible to the trainer’s antenna.
Wireless link between computers <> WiFi access point
Will you have control over the WiFi router in that space? As in - will you be able to specify what channels the 2.4Ghz and 5 Ghz signals will broadcast over? Will your players have exclusive use of that WiFi access point, or is it publicly shared?
If you have control over what channel the router broadcasts on - you can optimize the router to reduce RF interference in that space. I use an app called WiFi Analyzer to choose the best channel to use at home. It would be important to use the analyzer after all the trainers and computer in the room are powered on and creating RF noise of their own.
If you are able to specify the computer / tablet’s WiFi connection to use only the 5Ghz band - it would keep the WiFi connection from being stepped on by all the 2.4Ghz noise in the room (Bluetooth and ANT+ operate in the 2.4Ghz spectrum).
On the router end of the WiFi connection: IF all the computers running the Zwift app have WiFi connections that you can manually set to transmit in the 5Ghz space only - make the WiFi router operate only in 5Ghz (i.e disable the router’s 2.4Ghz radio). This way, the router isn’t putting out
unused 2.4Ghz noise that interferes with the Bluetooth and ANT+ connections. Make sense?
This is an article from Teradek, a company that makes wireless transmission devices for the broadcast TV industry, and some of it is relevant to your situation.
If you have control of the router - you might consider hard wiring as many of the computers as possible using Ethernet cable and a series of switches spread around the room.
Broadband connection between WiFi router <> ISP
If the router is public and you share the broadband pipe, such as you’re in a hotel conference room - you might talk to the facility’s IT admins in advance and ask if you might be assigned a private subnet and have raised QoS on that subnet for the duration of your event. It’s a big ask, but you never know.
Alternately, you might consider bringing one or more of your own WiFi hotspots, and assign several players’ computers to each one. This approach is at the mercy of the quality of the 4G data signal in that room.