I suggest upgrading to 2.4.48 to pick up this fix:
Fixed slapd-meta assertion when network interface goes down (ITS#8841)
While reviewing the changelog for 2.4.48 it had seemed to me that this fix was unrelated to the problem I had, because it was a different assert.
However, after upgrading 2.4.48 as suggested, and waiting about a month for safety, the problem seems to have disappeared entirely, so it was the same issue after all. Sorry about that, I think you can close this issue.