Unbound Serve expired; cache hit rate reducing with time

[sir izake]

Hi
I have installed unbound version: 1.20.0 on a FreeBSD 14 server. This was
working fine until the server lost internet connectivity to the upstream
internet provider. Prior to this the average cache hit rate on the server
was 99.0% with only 1% recursive replies.
Part of my unbound.conf file is shown below

server:
    prefetch: yes
    serve-expired: yes

# serve-expired-ttl: 0

 # serve-expired-ttl-reset: no

After loss of internet average cache hit rate has reduced to 14%
whiles recursive queries is showing 86% (still internet is not
restored)

My expectation is

Caching server should continue to serve expired and keep the cache hit
rate high because the serve-expired-ttl is default

(meaning it should continue serving cached content until upstream is restored).

My observation is the opposite.  Is there anything I am missing? How
can i ensure that the caching server will continue serving cache data
several days after upstream

internet is lost

Regards

Isaac
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