Frequent DNS Dropouts on base model UDM with various endpoints configured

I'll admit, my configuration is a bit of a cluster, but here goes:

I have different profiles set in NextDNS for each subnet within my physical network, each treating traffic a little differently based on my needs for what I want them to allow/block. Each of these is set via the provided IPv4 and IPv6 addresses within `Settings > Networks` and modifying each individual network's DNS settings to match what NextDNS provides for each profile.

Multiple times throughout the day, I run into name resolution failures. Pages will hang for minutes at a time, as if I'm being rate-limited by NextDNS for my volume of queries (I'm a homelabber, and have some chatty apps).

I'm unable to run the diagnostic tests or browse to https://test.nextdns.io during the outages to collect data, since name resolution is not working.

Effectively, I need to understand if what I'm doing (setting profiles with different filtering lists per subnet and configuring them individually on my UDM) is a supported use case and, if so, what can be done to make it so my DNS resolution doesn't die so often?