Fix issue of unreachable node after segment conflict

[maurerle]

After a conflict in a segment, some nodes generate a unreachable 2a03:2260:3006:115::/64 dev lo proto static metric 2147483647 pref medium route for the previous ipv6 network.

As this route is only valid for lo I am wondering why this has any impact at all, but it seems to lead to the node not being reachable from the previous mesh segment, which is weird.
Manually removing these unreachable entries then helps to resolve the siutation.

However, there is a patch from Freifunk Stuttgart which might cover this situation:
https://gitlab.freifunk-stuttgart.de/firmware/gluon/-/commit/62dbf788680d5d7a800466c07bf4e78691ee583c

We should test this patch or find a long term solution to this problem.

Yet, outgoing traffic which is not inside the mesh network is not affected by this issue.