No Ping when connected to a router

Hi Good day
I have a selfhost zerotier controller using ztncui UI on my own ubunto 20.04 VPS.
My nodes can ping together only when they are directly using the cellular network. with any router or modem, I tried, I get host unreachable when commanding ping.
I am somehow new to networking so please refer me to the specific tutorial if you can, it would be appreciated

I haven’t done any change to the planet, moon, orbit settings. all my nodes are being shown on ztncui as online and have an IP. Each node can ping with itself but not with others if that specific node is behind a router. I even tried turning of the firewall of one of my router but didn’t help.
I tried creating a new network, reinstalling zerotier on my server, and even a new server. the problem still exists…