Strange Ping-Behaviour

[MaT75]

My Proxmox-Host is located in a network 192.168.1.0/24.

I have a vlan 192.168.20.0/24 and in this Vlan I use two Linux Container and my IoT-Device. My Servers/Containers in this VLAN do not reach the IoT-Devices in the same VLAN for an unknown reason.

Ping from Linux-Container 1 (192.168.20.2) to IoT device (192.168.20.80) => Host Unreachable
Ping from Linux-Container 2 (192.168.20.3) to Linux Container 1 => OK
Ping from Linux-Container 2 to IoT-Device (192.168.20.80) => Host Unreachable
Ping from both Linux Container to Proxmox-Host (192.168.1.200) => OK
Ping from Proxmox-Host to all Devices in VLAN 20 (Containers *and* IoT-Devices) => OK

What may be misconfigured in my Container in VLAN 20 that they can ping each other but not the IoT-Devices? The IoT-Device ist a Shelly Dimmer

marco@homebridge-pm:~$ sudo ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.20.2  netmask 255.255.255.0  broadcast 192.168.20.255
        inet6 fd7a:b105:8c3d:4a5c:e0f4:68ff:fef2:e6b  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::e0f4:68ff:fef2:e6b  prefixlen 64  scopeid 0x20<link>
        ether e2:f4:68:f2:0e:6b  txqueuelen 1000  (Ethernet)
        RX packets 26960007  bytes 7371813635 (6.8 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5056916  bytes 1098960397 (1.0 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 502082  bytes 706720045 (673.9 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 502082  bytes 706720045 (673.9 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

 

[Spoonman2002]

A quick Google search shows that more people with a Shelly dimmer cannot ping this device.

Also, when I do a ping command from my PVE host (192.168.1.0/24) to any other vm in a VLAN, I get a time out.
(I use OpenvSwitch - OVS).
But again, isolating different subnets is the purpose of VLANs.

 

[MaT75]

But I can ping my dimmer but not from inside my vlan. From outside it is possible and that is what I don‘t understand.

 

[Spoonman2002]

But I can ping my dimmer but not from inside my vlan. From outside it is possible and that is what I don‘t understand.

Check your firewall/switch/VLAN config, because in theory you should not get a succesfull ping reply from other devices in (isolated) VLANs....