Ping OK only in one way


I’m facing an issue with ZeroTier.

Two devices :

1 - Raspberry pi + 4G key + ZT
2 - Windows computer + wired connexion + ZT

PC can’t ping the RPI
But If I ping the PC from the RPI : computer can now ping the RPI !

Do you know where is the issue ?

Your RPi’s firewall settings likely don’t allow pings. If you can ping in one direction only, that means that the connection works in both directions because a ping requires both sending & receiving a packet in order to get a result.

I d’ont know if you see the last sentence but after pinging the PC from the RPI, after that the PC CAN ping the RPI.

It’s linked to the RPI firewall ? or it’s an “issue” with Zerotier ? (routes problems or similar)

I try another thing :

I connect the RPI to the Wifi of my phone (in 4G/5G) : no ping issue at all
I connect again the RPI to the 4G key : same problem : if the PI don’t ping the computer, computer can’t see the PI.

And new thing :

RPI with 4G key and ZT : I can continuously ping, but if I try to ping computer : sometine ping is ok, someting no response…