AP Express (APXp) can be used as a scaled down version of Extreme, it supports fewer clients (50 vs 100 or so) and max out at 100Mbps on Ethernet ports. Current Express supports dual mode (2.4/5Ghz) but not AC, only 802.11n and does not have quite the range as Extreme. But in an AirBNB, these should not be issues.
I bring one along with AppleTV (ATV) and a MacBook Pro whenever I travel for extended stays. Main benefit is my SSID\Password are identical to home, so my devices operate as if at home. It also allows me to connect all my devices to my "Home WiFi" SSID even when the hotel\condo has web authentication requirements.
Setup:
- If there is an Ethernet port: Ethernet > APXp > Create a WiFi network
- If there is no Ethernet port: MAC WiFi (connect to hosts network) > Internet Connection Sharing (WiFi to Ethernet) > Ethernet > APXp > Create a WiFi network. This method works when host WiFi requires a web authentication like many hotels and rental condos, as well as a simple WPA\WPA2 WiFi.
- Alternate WiFi setup: If the host WiFi is simple WPA\WPA2 with no web authentication, setup one APXp in Client mode and join the host's WiFi, then a second APXp connected via Ethernet to the first APXp and Create A WiFi network as in the above settings.
In the first two cases the Express Network setting should be Off (Bridged Mode) as you don't want to create a second LAN with NAT\DHCP but allow the hosts router to do the NAT and DHCP for you. In the third case, network setting is Client Mode on APXp1 (this also turns WiFi off for client connections to this APXp), and Off (Bridged Mode) on APXp2.
I would assume most ABNB hosts have simple WiFi and no Ethernet so #2 or 3 would be the best bet. And, in place of a MAC, I think PC can do the ICS as well, but I have forgotten as much Windows stuff as I can.
The only thing you accomplish is a familiar WiFi for your devices. But, it is possible the host has a better WiFi setup so speeds on your "semi-isolated" WiFi may be slower than using the hosts 802.11ac network. If you bring an ATV along, make sure the name on it is distinct (FoulMouthATV rather than the default AppleTV). That way, you know which is yours if the host also has ATV.