> I have no router and the installer never prompted for an IP address. Two wireless stations could be connected using Ad-Hoc mode (so called iBSS) or using Access Point (BSS mode). If you do not have access point, you can try to configure Ad-Hoc: https://wiki.debian.org/WiFi/AdHoc
WiFi is a complex subject (much more complex than Ethernet based on copper twisted-pair cable), there is a whole book dedicated to Wifi administration: https://www.wiley.com/en-us/CWNA+Certified+Wireless+Network+Administrator+Study+Guide%3A+Exam+CWNA+107%2C+5th+Edition-p-9781119477501
