I've been hitting my head against this and can't quite figure it out.
My setup > Router is an RT2600AC, doesn't have the option to set PXE/TFTP through web-gui and had to make changes manually via SSH (when router reboots, settings are lost and again, have to make changes). [Will be brining this up with Synology support].
I cycle dnsmasq on the router, tail the syslog and I see the following:
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 available DHCP subnet: 192.168.86.0/255.255.255.0
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 vendor class: PXEClient:Arch:00007:UNDI:003016
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 PXE(br0) 50:65:f3:bd:b0:30 proxy
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 tags: br0
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 broadcast response
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 sent size: 1 option: 53:message-type 02
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 sent size: 4 option: 54:server-identifier 192.168.86.200
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 sent size: 9 option: 60:vendor-class 50:58:45:43:6c:69:65:6e:74
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 sent size: 17 option: 97:client-machine-id 00:7f:80:41:bc:f3:79:e3:11:99:04:62:a5...
Apr 8 09:49:37 WatchTower dnsmasq-dhcp[3985]: 273333721 sent size: 10 option: 43:vendor-encap 06:01:08:0a:04:00:50:58:45:ff
Apr 8 09:49:41 WatchTower dnsmasq-dhcp[3985]: 273333721 available DHCP subnet: 192.168.86.0/255.255.255.0
Apr 8 09:49:41 WatchTower dnsmasq-dhcp[3985]: 273333721 vendor class: PXEClient:Arch:00007:UNDI:003016
Apr 8 09:49:41 WatchTower dnsmasq-tftp[3985]: error 8 User aborted the transfer received from 192.168.86.169
Apr 8 09:49:41 WatchTower dnsmasq-tftp[3985]: failed sending /mnt/cache/appdata/tftp/pxelinux.0 to 192.168.86.169
Apr 8 09:49:41 WatchTower dnsmasq-tftp[3985]: sent /mnt/cache/appdata/tftp/pxelinux.0 to 192.168.86.169
Then on the box booting, I receive "An error occured with the boot selection verify media is present and retry".
I don't see the PXE menu on the client, just this failed white message on the screen.
If anyone could help point me in the right direction, I would really appreciate it!