IPv6 ULA-Prefix contains an invalid input value

Hi,
Thank you for the great work. OpenWrt is a pleasure!

I'm new with OpenWrt. I have installed the latest snapshot for my Fritz!Box 7490.

Now The Global network options shows me an error, see added pictures.
How can I solve it? What are a correct value for the IPv6 ULA-Prefix?

After every 4 characters you need a colon :

See https://en.wikipedia.org/wiki/IPv6

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Is there anything to consider for the IPv6 ULA-Prefix?

As I have read, the IPv6 ULA here should start with “fd” (local generated).
Would this address “fd34:9f29:2ba1::/48” be okay?

Did gyou enerated this or got it generated on first boot? Then yes.

I have generated the address. The wrong IPv6 ULA was generated at the first start, as can be seen in the picture from the first post. I had not changed anything deliberately. Can I have the PIv6 ULA regenerated by OpenWrt?

I've found the following article, which also refers to an incorrectly created IPv6 ULA prefix.

The article refers to an the OpenWrt 12_network-generate-ula. This script is not to be found at /etc/uci-defaults. If I execute the part that generates the ULA prefix manually, I get an incorrect prefix.

root@OpenWrt:/etc/uci-defaults# echo "$(hexdump -vn 5 -e '"fd" 1/1 "%02x:" 2/2 "%x:"' /dev/urandom):/48"
fd52:92440092:fec900fe::/48

The output looks similar to the IPv6-Prefix in the picture from my first post.

May it be possible that the snapshot image for the fritz.box 7490 uses the wrong script to generate the ULA-Prefix?

There must be something wrong with your version of hexdump. The command run on an ath79 router with OpenWrt 24.10.1 generates a correct result.

root@MSL:~# echo "$(hexdump -vn 5 -e '"fd" 1/1 "%02x:" 2/2 "%x:"' /dev/urandom):/48"
fdb6:12fa:c2c4::/48

The address itself is merely fd then 10 random hex digits, separated by colons in the right places.

uci-defaults scripts erase themselves after running once. In a squashfs image the original copies remain in /rom/etc/uci-defaults