So far the internal Orbi WiFi and fixed network has stayed up. What’s more significant is that when we are watching a streaming service, such as Disney+, there are no more buffering waits (where a swirling icon appears on screen and the video stops playing). Throughput seems to be much better. I can attribute this more to (I believe) disabling DST than I can to changing my NTP server to an official NIST time service, although any service I can switch away from Netgear, the happier it makes me.
If what I did to solve this is the case then we’re talking about a fairly significant bug in the Orbi firmware supplied by Netgear, which is why I’m so interested in replacing it with an official OpenWRT image rather than the one Netgear wants us to use.