Question Wake on LAN - Turning ON a PC directly connected to main router from a sub router

Jun 5, 2021
WOL is not working when the target PC is completely off (G3) and directly connected to the main router and the WOL broadcast is coming from a device that is connected to the child router of the main router but it works if the target PC is in sleep mode.
Also, the target PC starts if the broadcast is coming from the device that is also directly connected to the main router.
The broadcast device can be a PC or a mobile phone.

How can I solve this problem?

You said the key word in your post "broadcast". WOL is broadcast packet sent to the LAN. Broadcast packets never leave a subnet. You are attempting to send a packet to something on the WAN. There is no such thing as wake on WAN

WOL has no concept of IP addresses it is purely uses MAC addresses, again because it is a LAN protocol not a WAN protocol.

Now there are many tools that pretend that you can use IP addresses and they to a point work in WAN but they do not consistently. Most times they will work for 5-15 minutes and then fail. IP addresses require a ARP entry in the router to translate the IP/mac. This will time out and will not be repopulated because the machines does not respond to ARP when it is WOL mode.

You would need to put static ARP entries into the router which almost no consumer router supports. In addition some consumer routers send all traffic to the gateway even when it is on the same subnet on the WAN port

If sleep mode works I would just use that. There is almost no difference in any power savings.