Unbound issues when losing IPv6

[mooh]

Just FYI:

At a site where an OPNsense is connected to the internet via a Telekom DSL router with LTE fallback, the fallback does not provide IPv6. In addition to the obvious problems with that, I found that unbound fails frequently with messages like

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error: SERVFAIL <ocsp.edge.digicert.com. A IN>: exceeded the maximum number of sendsIt appears that unbound continues to contact nameservers via IPv6 even after repeated failures, not reverting to IPv4 automatically, thus impacting even IPv4 connectivity.

A quick hack to restore IPv4 connectivity completely is to set "do-ip6: no" in the "server:" section of unbound.conf and reload.