Secondary DNS doesnt get picked up if Primary DNS is down

[vitachaos]

I have a primary dns server running at home network which I have filled in to the router configuration from the router home page. Since right next  to it, there is an option for secondary dns I have pointed it to cloudflared 1.1.1.1 public dns as a failsafe. However when my home dns is down it never gets picked up and internet on all devices at home halts

[KeithFrench]

Can you ping 1.1.1.1 from one of the affected devices?

[KeithFrench]

I assume that you are using the Huawei DG8041W router then? Where in the router are you setting the DNS servers up, I assume that it is in the router's DHCP server configuration, so each device is told on connection, that these are the two DNS servers to use?

Do the devices actually store this, in Windows, for example, using this in the command prompt will tell you:-

ipconfig /all

If the device has these stored, then it is down to the device to decide which DNS server to use.

However, if all devices are correctly storing the DNS servers & none of them can use the secondary DNS server, that is bizarre.