If I have an iPhone 12 Pro and an iMac M1 Running a LAN speed test over WiFi to 2 different Synology NASs the WiFi speed drops down to a crawl. Each NAS has a speed test server that on a 1GbE cable clocks at 980Mb/s. Having OFDMA off the speed is about 130Mb/s per device. With OFDMA on the speed per device is about 14Mb/s per device. The iMac alone will run the test at usually about 700Mb/s. Why is does if slow down so much? I'm wondering if this is an issue or a weakness of WiFi being hammered this way.

The 2 NASs are wired to a NetGear GS108Ev3 switch that is wired to an AX73 router LAN port.