[FrankJ]

We routinely run 6 robots (different team numbers) thru one Dlink. So that by itself is not the issue. Possible issues could be multiple radios with the same SSID set to AP mode rather than bridge mode. There can be only one. Robots sending a lot data from cameras, etc. This is limited by the hardware on the First fields. A noisy environment. 5 gHz seems to be a cleaner than the 2.4 gHz band.

Other than that, use separate a SSID as Mark suggested.