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My pi-hole is, so far as I know, entirely "standard." It's running on an RP4 with 4GB of RAM.
I expect network access to be stable and consistent.
The pi-hole has been running for a few months with no issues whatsoever. Then, perhaps a week or so ago, my home network seems to go offline once a day. Sometimes it makes it two days. When this happens, checking the IP address on what is normally a DHCP client shows that it's not receiving a lease. Setting a static IP on the client with DNS pointing at my router brings that client back online. Likewise, rebooting the Pi brings everything back up in about 5 minutes or so.
My suspicion is that this has to do with the pi-hole not serving DCHP leases correctly, not resolving DNS correctly, or some combination of both.