HELP! I'm new, pihole is not working as expected. please help me

[hoaduy994]

I am new, I am deploying DNS server with pihole, machine 1 is 10.235.x.x is Ubuntu 20.04 and machine 2 is 10.233.x.x is Ubuntu 20.04, after installation is complete I use DNSperf with 1 sample data with 1 million domains to test DNS resolution performance in 60 seconds with 20 clients from another computer, not 2 computers 1 and 2 above, it has ip 10.235.y.y above is ubuntu, we see that machine 1 receives all requests and will not affected. is rejected or has errors, but with the second computer, with the same testing method, it is rejected and has many errors about 10 - 20%. I have installed and configured all piholes with allow all, the configuration is still the same. How to make pihole accept every request without errors or rejections. And another problem is that computer 1 suddenly cannot resolve DNS anymore and is offline for a period of time. I need help !.
computer 1

computer 2

Debug Token:

https://tricorder.pi-hole.net/44QDH2Ix/

[Bucking_Horn]

What you observe seems expected:
If you swamp your Pi-hole with millions of DNS requests within 60 seconds, either Pi-hole's or its upstream DNS resolver's rate limits may kick in.
In additon, on restricted systems, that amount of requests may also cause memory shortage. In a worst case, that may even prompt OS OOM kills when memory is critically low.

[hoaduy994]

How can I fix it? I've been stuck for a long time

[hoaduy994]

I have set the rate limit to 0/0