Can i force Client mode to use 2.4Ghz band?

New user here, trying to build up a thin client with a bunch of VMs to help me teach at conferences. They are Dell 7070s with Intel wifi cards. I need the card to both act as AP and client at the same time. (I have OpenWRT running in a container and passed the wifi card to it). I can get both to work at the same time as long as the client stays on 2.4Ghz (as i come to learn dual band cards means "one at a time though").

So conference centers where they use one SSID for both bands will present a problem, as the wifi card jumps to 5Ghz and then breaks AP mode, since AP mode isn't supported at 5Ghz (or at least i can't make it work).

So am i missing something in the setup where i can force the client config to stay on 2.4Ghz? I tried locking to the BSSID of the 2.4Ghz AP, but it seems if band steering is on then they fight each other and never connect at all.