hello, try :
option sendopts '57:XXXX'
i think the XXXX has to be replaced by the length of your message size in hex value (16bit).
you can check in wireshark how the default 576 value is sent. just do the same and increase/reduce the value. i think you should see 0240 somewhere.
thanks ! add option "sendopts '57:XXXX'" to which file? /etc/config/dhcp ?
i chaged it in /etc/config/network. but Something strange happened . the discover message has two option 57
576 and 1500
it depends on what you're doing...
it could be in /etc/config/network or as you said in /etc/config/dhcp
Maybe because this option is already calculated by the system (udhcpc or dnsmasq) ? i don't know...it's the first time i see someone trying to change this value.
i'm wondering where we can find some information about udhcpc, in order to know what dhcp options are supported by the client...
i can see here : https://busybox.net/ that all options are not supported, because sometime some people add options :
this was added : 10 June 2019 -- BusyBox 1.31.0