Primary DNS down, lost internet

Hi,

I have two PiHole's in my network. 192.168.1.5 and 192.168.1.6. 192.168.1.5 is the primary DNS and .6 ois the secondary DNS for my WAN network, Today I removed PiHole from my primary machine and my internet went down.

• 192.168.1.5 was online and PiHole uninstalled, nothing on port 53
• 192.168.1.6 was online with a working PiHole

Why did it not failover to the secondary DNS?