My goal is to interface with several web servers and a remote programming ide running on a raspberry pi 4 which is connected to the router via ethernet. I’m accessing it by connecting to the wifi network which the router is broadcasting. My reasoning for this is that my home wifi network is shared amongst several tenants and uses a strict firewall which blocks access to the pi via ssh, vnc etc. So far this setup is working very well, but yesterday the home network went down for small period of time and I was unable to access the pi and continue working.
If internet access for devices is not my top priority, and connectivity between devices on the network is, what would be the ideal way to configure openwrt?
The problem is that the STA interface (your wireless uplink) must be the master interface, your AP interfaces can only come up after the STA link has been established (as this is the one determining essential link parameters, like the used channel). If the STA interface goes down, so does the AP interface - this is a technical stacking dependency and 'unfixable'.
The ideal solution to this would be to use a dedicated radio for the wireless uplink (e.g. tri-radio mesh APs), which would keep STA- and AP interfaces independent on different radios.
The travelmate package tries to reduce downtime as a workaround, it's technically still there, but its impact is lessend via reactive reconfiguration.
As stated by slh, all wifi-iface will standby waiting for the station (client) interface to go UP first. The operating frequency (or channel) needs to be determined by the station interface before the other interfaces can go UP.
And you can rely on a network manager (travelmate package -- I never try it), or use one radio for station, and another radio device for repeating/relaying.