Network boot cannot boot more than 3 random PI's

[ghost]

I have 48 Raspberry PI's booting from a x86 Raspbian Desktop.
If I boot only 1, then it boots. Every one of the 48 can successfully networkboot.

However, it they are booted together only 1-3 random PI's manage to boot.
I tried: exchanging tftp services. (TFTPD just seemingly got "stuck" after one PI), PiServer (Managed to boot 3-4 then it didn't work), dnsmasq reply delay, socat pinging to 244.0.0.100. Nothing seems to work.
dnsmasq-tftp manages to boot 3 Pi's, but not more.
All the PI's receive a DHCP reply. According to dnsmasq logs all PI's try to boot. But only 3 succeed at a time, all the other ones get failed sending errors.

log from syslog grep tftp.txt
dnsmasq log attached, with 6 connected for easier reading. Funny enough, the one's that had the "error 0 Early terminate received" were the one's that booted in this log. (192.168.3.31 and 192.168.3.40)

I am truly at a loss.

[maxnet]

Sniff the DHCP traffic instead of tftp, and check if the DHCP server is perhaps assigning the same IP-address to more than one MAC addresses.

Potentially related to the issue mentioned at the bottom of: #991
If it is, and you are able to alter the configuration of the DHCP server that is responsible for assigning the IP-addresses, a workaround would be to configure static MAC<->IP assignments.