Shelly Power Strip Gen4: local access works, but no cloud / no time sync on main home Wi-Fi, while hotspot and guest Wi-Fi work

    • Autor

    Hi everyone,

    I am trying to troubleshoot a strange issue with a Shelly Power Strip Gen4 and would appreciate any ideas.

    Problem description

    When the device is connected to my normal home Wi-Fi, it is locally reachable without any problems, but:

    • no cloud connection
    • no time synchronization
    • in the Shelly app the device shows “Pending connection”
    • in the web UI I get the warning that the device time is not synced
    • after reboot, the device time falls back to 01 Jan 1970

    So the device is clearly on the network and reachable locally, but it does not complete cloud/NTP communication in the main home network.

    What works locally

    On the main home Wi-Fi, local communication is fine:

    • web interface reachable via local IP
    • ping works
    • HTTP on port 80 works
    • PowerShell Test-NetConnection to port 80 succeeds
    • Invoke-WebRequest returns 200 OK

    So this is not a basic local connectivity issue.

    Environment

    • FRITZ!Box router
    • FRITZ!Repeater in the network
    • ioBroker in the home network, so I need the Shelly to stay in the main LAN/home network segment
    • guest Wi-Fi is not a real long-term solution because I need local access from ioBroker
    • Wi-Fi security: WPA2
    • 2.4 GHz and 5 GHz available
    • the Shelly is on 2.4 GHz
    • I also tested 2.4 GHz in a more compatible mode (Wi-Fi 4)

    What I already tested

    I have already tried all of the following:

    • factory reset of the Shelly
    • re-adding the device from scratch
    • using different NTP servers:
      • time.cloudflare.com
      • time.google.com
      • pool.ntp.org
    • manually setting date/time through the browser
    • static IP on the Shelly:
      • IP 192.168.111.101
      • subnet 255.255.255.0
      • gateway 192.168.111.1
      • DNS 1.1.1.1
    • FRITZ!Box DNS changed from ISP DNS to public DNS
    • Pi-hole / Unbound temporarily removed from the setup
    • IPv6 temporarily disabled for testing
    • Wi-Fi adjusted to WPA2
    • 2.4 GHz adjusted to Wi-Fi 4 for compatibility

    Important observations

    This is the key part:

    On my main home Wi-Fi

    • local access works
    • cloud does not connect
    • time sync does not work

    On a phone hotspot

    • cloud works
    • time sync works

    On the FRITZ!Box guest Wi-Fi

    • cloud works
    • time sync works

    That strongly suggests:

    • the Shelly device itself is fine
    • cloud and NTP are not generally broken
    • the issue seems specific to my main home Wi-Fi / home network profile

    Additional details

    I also checked DNS-related behavior earlier and could see queries for things like:

    • api.shelly.cloud
    • iot.shelly.cloud
    • updates.shelly.cloud
    • time.google.com
    • time.cloudflare.com

    So at least DNS resolution seemed to happen at some point, but the actual cloud/NTP communication still fails on the main home network.

    What makes this confusing

    What I do not understand is this:

    • on the main home Wi-Fi, the device is reachable locally and behaves normally in local access
    • but cloud/NTP fail
    • on the same internet connection, the guest Wi-Fi works
    • on a phone hotspot it also works

    So the problem seems to be tied very specifically to something about the main home network / main SSID / FRITZ!Box home network behavior, not to the Shelly hardware itself.

    What I need

    I need a solution that lets me run the Shelly inside the normal home network, because ioBroker needs local network access to the device.

    Using the guest Wi-Fi is only useful as a diagnostic test, not as a permanent setup.

    My question

    Has anyone seen similar behavior with Shelly Gen4 devices on a FRITZ!Box?

    I would be especially interested in:

    • known differences between main home Wi-Fi and guest Wi-Fi that could explain this
    • anything FRITZ!Box-specific that could block cloud / NTP only on the main network, while local access still works
    • any Shelly Gen4 quirks with FRITZ!Box, FRITZ!Repeater, mesh, or specific Wi-Fi profile settings
    • ideas for how to keep the device in the main home network so that ioBroker can access it locally

    Thanks in advance.

    Hello,

    a Shelly Gen4 connected to the FRITZ!Box's main Wi-Fi network can establish local connections, while cloud and NTP services fail, often due to restrictions in the access profile. Since the device connects correctly via a hotspot or guest Wi-Fi, a defect is unlikely, and the problem is limited to the main network.

    Suggested solutions:

    Check under Internet > Filters whether the Shelly is assigned the "Unrestricted" profile to avoid parental control restrictions.

    As a test, disable "Packet Acceleration" under Content > FRITZ!Box Support.

    Enter shelly.cloud under Home Network > Network > Network Settings > DNS Rebinding.

    The most likely cause is an active block on NTP (port 123) or cloud ports in the FRITZ!Box's default access profile.

    good luck!


    PS: Alternatively, enter the IP address of your Fritzbox (=Gateway) in the DNS settings on the Shelly device.

    Einmal editiert, zuletzt von AmiVanFan (1. April 2026 um 23:40)

    • Autor

    Hello,

    thanks for the suggestions.

    I tested all of the points mentioned:

    • device set to Unrestricted
    • checked access profiles / filters
    • tested DNS rebinding exception
    • tested the other suggested FRITZ!Box settings

    Unfortunately, no change.

    What makes this especially strange is that I am running around 20 other Shelly devices in the same network without any issues at all. They work normally with local access, cloud connectivity, and time sync.

    Also:

    • the Shelly Gen4 works on a phone hotspot
    • it also works on the FRITZ!Box guest Wi-Fi
    • only on the main home Wi-Fi it has local access, but no cloud and no NTP/time sync

    So at this point it really looks like a very specific compatibility issue between this Gen4 device and the main FRITZ!Box home network profile, rather than a general problem with my network or with Shelly devices in general.

    If anyone has seen this specifically with Gen4 + FRITZ!Box main Wi-Fi, I would be very interested.

    Since you've already verified the access profiles and DNS settings, and the device works fine in the guest network, we should focus on the FRITZ!Box's internal device management for your main network.

    Please try the following 'clean-slate' approach:

    1. Remove the device from the FRITZ!Box database:
      Go to Home Network > Network. Disconnect the Shelly Gen4, find it in the list (it might move to 'Inactive connections'), and delete it completely by clicking the red 'X'. This clears the internal routing and ARP cache for this specific MAC address.
    2. Reconnect via DHCP:
      Restart the Shelly and let it join the main Wi-Fi again using DHCP (do not set a static IP on the device itself yet). Check if it now successfully completes the NTP sync and cloud connection.

    If this works, you can still assign a 'fixed' IP via the FRITZ!Box setting 'Always assign this network device the same IPv4 address' afterwards

    • Autor

    Solved / final update

    I found the solution.

    In the end, the problem was not caused by cloud settings, NTP server settings, DNS, Pi-hole, Unbound, IPv6, Wi-Fi mode, or a defective Shelly device.

    The fix was simply to change the IP address of the Shelly Power Strip Gen4 in my home network.

    Symptoms before

    With the original IP address, the device was:

    • reachable locally via browser
    • reachable via ping
    • connected to Wi-Fi

    But at the same time:

    • no cloud connection
    • no time sync
    • the app showed “Pending connection”
    • after reboot, the clock went back to 01 Jan 1970

    What made this especially confusing:

    • it worked on a phone hotspot
    • it also worked on the FRITZ!Box guest Wi-Fi
    • only on the main home Wi-Fi the problem appeared

    What solved it

    After changing the Shelly’s IP address, everything started working normally again:

    • cloud connection
    • time sync
    • normal app connection

    Likely explanation

    Most likely there was some kind of conflict or stale network state related to the previous IP address, for example:

    • old DHCP lease
    • ARP/cache issue
    • router-side stale entry
    • some internal inconsistency tied to that address

    So if someone sees a similar case where:

    • local access works
    • but cloud and NTP fail
    • while hotspot or guest Wi-Fi work

    then it is definitely worth testing the device with a different IP address.

    Maybe this helps someone else.

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