When you use Pi-Hole as your DNS server, the DNS server on the client devices should be the Pi-Hole’s IP address, not the Brume’s IP address. You can change what the DHCP server sends to clients via LuCI → Network → Interfaces → LAN → Edit → DHCP Server → Advanced Settings → DHCP-Options. I don’t think the GL.iNet UI has this setting, but not sure.
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