Workaround:
A little script solve the problem. In the ICS-file at HOME directory will the „BYMONTHDAY“ part deleted.

sed -r 's/INTERVAL=1;BYMONTHDAY=[0-9][0-9]?/INTERVAL=1/g' /
~/mycalendar.ics

Many, many THANKS to you. I‘m happy that you resolve this problem

@sdetweil I sent you the mail to your account. Thank you in advance

@sdetweil Can I sent you a board mail?

And here a picture - SORRY german only

The Lines marking the events out of date range
red: december
blue: august
yellow: july

@sdetweil No problem, the url’s are not a secret :-).

{
	module: "calendar",
	position: "top_left",   // This can be any of the regions. Best results in left or right regions.
	fetchInterval: 240000,
	config: {
		maximumNumberOfDays: 30,
		maximumEntries: 10,
		getRelative: 0,
		calendars: [
				{
					symbol: "birthday-cake",
					url: "http://localhost:8080/modules/default/calendars/1.ics",
			},
				{
					symbol: "calendar-check-o",
					url: "https://www.zaoe.de/ical/8231/_1-3-4-6/23/"
			}
		]
	}
},

Hello Together,
My MM use the standard calendar modules. And the data come from an import via vdirsyncer ICS file. The calendar shows all events with the same day include from outside of the defined range in config file.

Parameters in CONFIG.JS:
MaximumNumberOfDays: 30
MaximumEntries: 10
GetRelative: 0

Example:
at date 2022/03/07 will show

• Birthday of Jan-Peter Friday 03/11/2022
• Party at Rico Friday 06/11/2022
• Wedding anniversary Sunday 08/13/2022
• …

It looks like a filter is „ill“…

Any ideas?

THX, Uwe