Hi, I've been trying this out on my router, and it seems okay but:

1. Apparently the DNS Cache only has "up to 4MB" of storage available for the records. Why is it so tiny?
2. How can I extend this - is it extendable?
3. Is there a recommended minimum TTL value for this router that might be recommended for SOHO use that won't blow the cache storage limit?
4. I tried TTL= 86400 (24 h) but I started to receive email log messages that say:  "SYSTEM WARNING The number of logs is up to the limit." Strange thing is there's nothing in the OC200 Controller info that shows *any* logs of any kind! I've now cleared the TTL value so that did flush the cache when I cleared it but still, there's no logging anywhere that I can see other than the content of the DNS Cache itself.
5. As can be seen in the screen snip attached, the TTL help in the Parameters section says: "If it's not specified, the system will use the default TTL value of each DNS message." Should I just be happy with that? Some of the message defaults range from 100 secs up to about 300 secs (5 min), which kind of seems short, but the system is operating okay (I'm deliberately not showing my cache contents here!)
6. I'd still like some way to track the amount of cache storage in use so I can figure this out for my own installation. I can't seem to find anything.
7. I've configured the DNS Proxy for DoT via Quad9 and OpenDNS (see second screen snip). While it seems to be working okay is there any way to set the priority? 
8. With OpenDNS, it seems the "familyshield.opendns (DOT) com" is the fastest responder that's not my ISP, although other non-shield servers come in shortly after that. See 3rd screen snip. is there a way I can exclude the ones I don't want when I check the OpenDNS box in the Omada config for the router? Perhaps I can add the preferred ones manually I guess, with the "Add Custom Servers" feature, but that only lets me add IPv4 addresses, not IPv6.
9. and yes, I do know I can use something else like a pihole to build a DNS cache but then I can't manage that under the Omada umbrella.

Thanks and kind regards,