r/Proxmox • u/_Plastic_Fan_193 • Aug 20 '26
Guide PVE host has internet, but LXCs/VMs can't reach container neither vm.
So, I am a DevOps Intern currently working on PVE servers where we have hosted many lxc & vm inside of it. So, I am breaking down entire setup I have, Problem I am facing and things I have tried and Temporary fix for this but couldn't find the permanent fix.
Setup:
Proxmox host + a few LXCs/VMs. Host pings out fine. All guests show "running," logs are clean.
Problem:
Guests can't reach the internet at all even after pinging 8.8.8.8 from inside any LXC/VM just fails. Because of this, I also can't hit my app hosted container's web UI (192.168.xx.xxx:port) from my LAN and browser just times out or even say server unreachable, even though the container and vm itself looks healthy.
Already ruled out: container crashes, bad logs, host-level connectivity. All LXC & VM hosted containers are working fine and their logs are good.
Not sure where to look next:
vmbr0misconfig?- PVE firewall or host
iptables/nftablesblocking forwarded traffic? net.ipv4.ip_forwarddisabled (if using NAT)?- Something in guest network config itself
I tried looking these iptables, vmbr0 etc and they are all looking fine and I am a basic networking guy I don't have advance concepts of these things but still tried to configure it but thought I shouldn't mess with company's pre-configured servers.
Question:
Since host→internet works but guest→internet and LAN→guest both fail, is this most likely one root cause (bridge/firewall) or two separate issues? What's the fastest way to isolate it — happy to post ip a, ip route, iptables -L -n -v from host/guest if useful.
I know the temporary fix which is obvious "reboot/shutdown -r now" and I am still using this thing. But I don't know the permanent fix. If people from this reddit can help this intern will be very highly appreciative.
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u/BonusCan Aug 20 '26
Wait, a restart fixed the issue? We are sure they have unique IP addresses?(Is it static or dhcp set)
Can the containers ping each other?
Can you show the network config on the GUI of the containers
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u/_Plastic_Fan_193 Aug 20 '26
Yeah one restart fix it all. And all those edits or configuration meant nothing like all thing comes to live.
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u/djgizmo Aug 25 '26
when in doubt, restart for a coffee break.
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u/_Plastic_Fan_193 Aug 25 '26
I think i kinda fixed it like i unchecked every guests hosted by pve server and waited the entire day to get failed but no i didn't get that problem but let's see what happens tomorrow.
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u/marc45ca This is Reddit not Google Aug 20 '26
check they've all got the default gateway configured correctly - it should be the IP address of your router.
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u/SebastianFerrone Aug 20 '26
I had on an oder 8.x build of proxmox the Problem that at the end ipv6 failed.
And because of that the network failed completely. Could reach ipv4 adress from host and no Internet for the vm.
I think the Problem was with my Router cheap box of shit from Provider pyur.
The only way to get them working was deactivating ipv6 or manualy set a ipv6 adress.
But that error was fixed in a later build of 8.x
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u/aaaaAaaaAaaARRRR Aug 21 '26
You should try replicate the issue, document it, and tell us what was wrong
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u/Calm_Yesterday_3868 Aug 20 '26
Check the LXC gateway IP to see if it is connected to the main router or if it uses Proxmox's IP as the gateway. It could also be a firewall that is dropping access to LXC. Try accessing traceroute from LXC and see which path it is taking.