I followed Ingo's excellent description how to set up the Pi (running latest, fresh version of buster) as an access point, routing to either a wifi dongle or an umts-stick. Everything works, except one issue:
- when connecting just the wifi dongle, system comes up immediately.
- when connecting just the umts stick system needs >60sec to come up.
Using journalctl I see that systemd waits for the wpa_supplicant job trying to setup the (non-connected) wifi dongle and times out after about 60sec. My internet search pointed to "systemd-networkd-wait-online.service" and modifying timeouts etc. - however this service seems not to be active/used on buster.
UPDATE with information from a comment:
Configuration was made for both the wifi dongle and the UMTS-stick and both of them work fine as an uplink. I am using it on a boat and only connect one of them at a time depending on the availability of a wifi hotspot or the necessity to use UMTS. The only issue is that when I connect just the UMTS-stick and leave the wifi dongle unconnected systemd (wpa_supplicant) hangs until timing out after about 90 sec and the whole startup process is delayed. I could not find a way in the configuration to reduce the delay or make the wifi dongle "optional".
UPDATE2: The issue of the startup delay is NOT related to the UMTS-Stick. Same occurs when neither wifi dongle nor UMTS-stick is connected as an uplink and immediately goes away when the wifi dongle is connected (regardless of the UMTS-stick being connected or not). Journalctl clearly shows wpa_supplicant waiting for the uplink on the (in that case not connected) wifi dongle as the cause of the delay until it messages a timeout after about 90sec. The reference to systemd-networkd-wait-online.service as causing this did not help as this service is not even active (according to systemctl status) - which I only realized after the referenced settings did not make any difference. Info about the UMTS-Stick: It is a Huawei E300 which registers automatically as an ethernet device (eth1) and (according to journcalctl) comes up a few seconds after boot. Coniguration is thus extremely trivial. Just this .network file:
DNS=18.104.22.168 22.214.171.124 126.96.36.199