Ah, sorry I thought I was in the DAVdroid forum… With ICSdroid you can always set the minimum interval that you need for one calendar, the others only get updated when there are changes on the server so there is no unneeded traffic. See here because we’re often asked about it:
Stuck in Validating Calendar Resource
I’m trying to import a private Google group calendar (GSuite calendar), but it gets stuck in “Validating Calendar Resource…” and loops forever.
I can access and download the ICS file through a browser without any problem (without having to log in, etc).
When I look into logcat, I see the following:
java.io.FileNotFoundException: /data/data/at.bitfire.icsdroid/app_KeyStore/KeyStore.bks: open failed: ENOENT (No such file or directory) Failure retrieving resources for at.bitfire.icsdroid: Resource ID #0x0
On version 1.4.2 downloaded from F-Droid.
The calendar URL is in the form of: https://calendar.google.com/calendar/ical/GROUP_DOMAIN_XXX%group.calendar.google.com/private-YYYY/basic.ics
Note that it works fine with a personal private ICS URL (belonging to the same G Suite group/organization).
Same happens when loading the ICS file locally.
It seems that the location provided does not work. Maybe some kind of weird redirect or so. Also keep in mind that Google answers very slow on some .ics requests - I had this once myself. Maybe just try again?