UDP client behaving differently for wifi router

Question

I have a setup like, main router is connected to modem(ISP), I have connected one wifi router to main router, and another wifi router to above wifi router, so have 3 levels of routers. Now I connected one UDP client to wifi router at level 2 and other UDP client to wifi router at level 3, and tried to send/receive packets, but they were not able to receive packets.

I tried running skype for same setup but skype was also not able communicate peer-to-peer, it was sending packets through servers.

Also when I am connecting one client with main router and other client at any level of wifi router then they are able to communicate.

Help needed... Thanks in advance.

Answer 1

Disable NAT on your 2nd and 3rd routers. If your routers don't provide a way to disable NAT, then stop using their WAN ports; just daisy-chain them LAN to LAN to LAN. Hopefully they provide a way to turn off their DHCP servers; otherwise you should set the DHCP pool/range to zero-length on all but the first router.

If the ISP modem is more than just a modem and actually does NAT and DHCP as well, then you should stop doing NAT and DHCP Server on even your first Wi-Fi router.