There is a very active thread on Reddit regarding Orbi's that stopped being able to resolve DNS after the Daylight Savings Time change:
https://www.reddit.com/r/orbi/comments/m5l3vk/orbi_dropping_dns/

Since it appears that NetGear is unable to fix this or even acknowlde it exits, I will share the options that you can use to resolve them here as well:

"Fixes" So Far - These each work with various levels of pros and cons:

A) Router Reboot:
Manually reboot RBR when issue arrises
(obviously not a great fix)

B) Configure Clients Manually:
Manually configure your preferred DNS servers on all of your clients
(This is not a practical solution for most people - some devices don't support this, and it makes it harder for guests)

C) Restart DNSmasq:
1-Enable telnet on your router using the <router>/debug.htm page
2-Telnet into your router and use the "/etc/init.d/dnsmasq restart" command to restart the DNSmasq service when the issue arrises
(Also not a great "fix")

C.i) Automate DNSmasq restarts:
This is a variation on the option above, which uses a cron job to schedule the dnsmasq restart command to run periodically by telnetting into the router and use "crontab -e" to add the line
*,30 * * * * /etc/init.d/dnsmasq restart
(This works, but requires some knowledge to implement and modifies your configuration files, which has potential to introduce new issues)

D) Modify DHCP:
The problem we are all having is that the Orbi gets into a state where it cannot resolve DNS. The Orbi implementation of DHCP configures our clients to use the ORBI router as the DNS server (instead of our preferred DNS servers). Using this method, you can modify the configuration of the Orbi to actually use its DHCP server to configure your clients with your preferred DNS server.
1-Enable telnet on your router using the <router>/debug.htm page
2-Telnet into your router and use vi to edit the "/tmp/udhcpd.conf" file
3-In vi, move the cursor down to "option dns" and modify the IP there to DNS server you want to push to your devices
4-Use the :wq command to save your edit and quit vi
5-Kill the currently running DHCP server, and restart it using these commands as an example:
ps | grep udhcpd 15716 root 1568 S grep udhcpd 19158 root 2452 S udhcpd /tmp/udhcpd.conf
 cat /var/run/udhcpd.pid
 19158
 kill 19158
 udhcpd /tmp/udhcpd.conf
 udhcp server (v0.9.8) started
(This option works, but requires technical skill. This "fix" will not survive a reboot, which is good and bad. You can "undo" what you did with a reboot, but you will also have to redo this "fix" whenever your router reboots - this is a reasonable solution until the bug is foxed in a firmware update)

E) Install a DHCP Server:
Use/Install another device (your cable modem, a PiHole, bootpd on macOS, etc) as a DHCP server:
1-Disable DHCP on your Orbi
2-Configure your DHCP server with the settings you want
(This option works well if you have a DHCP server handy and don't mind maintaining another piece of gear. It might provide a better—or worse— interface to managing DHCP than the Orbi interface)

F) Modify NTP Settings:
1-Uncheck the "Automatically adjust for daylight savings time"
2-Change your timezone "east" one hour to accommodate turning off the auto DST.
3-This step is probably optional: Change the NTP server to 1.pool.ntp.org
(Disclaimer: I have not tried this option, but the person who has indicated this has been working for 20+hours. If this option works it is probably the best option for most people to implement, as it is easy to change and unchange once the bug is fixed)

Forum Discussion

Orbi DNS and DHCP and NTP Broken - Short Term Fix Options