LOGO! 8 Web Server Mobile Access: Troubleshooting IP and DHCP

Problem Details: LOGO! 8 Web Server Not Reachable from Mobile

The LOGO! 8 (6ED1052-xxx08-0BA1/0BA2) logic module ships with an onboard Ethernet interface and an integrated Web Server (V1.0.0 and later) that exposes the on-line monitoring page at http://<logo-ip>. A recurring field issue is that the same Web Server opens correctly from a PC connected by cable, yet the page refuses to load when the operator opens the same URL from a smartphone or tablet on the same Wi-Fi. Symptoms include:

• PC (wired) loads http://192.168.1.10 immediately; phone on Wi-Fi returns "site cannot be reached" / "ERR_CONNECTION_TIMED_OUT".
• Phone can browse the Internet fine, but cannot see the LOGO!.
• Phone pings the router but not the LOGO! IP.
• Browser displays a security block ("Your connection is not private", certificate warning, or "unsafe site blocked").

Root Cause Analysis: Why the Phone Fails While the PC Works

When the wired PC works and the wireless phone does not, the failure almost always sits in one of four layers between the phone and the LOGO!. The fix is to localize the failing layer first, then correct the configuration.

The most frequent root cause reported in the field is the IP / subnet mismatch: the LOGO! is configured with a static address (e.g. 192.168.0.10) that is outside the DHCP / subnet scope of the consumer router (e.g. 192.168.1.x / 255.255.255.0). The PC happens to be on the correct subnet because its NIC was manually configured the same way, while the phone receives an automatic address in the router's range and can no longer route to the LOGO!.

Pre-Flight Checklist: Confirm the Web Server Is Actually Enabled

Before chasing the network, verify the Web Server is published in the project. Open the LOGO! project in LOGO! Soft Comfort V8.x and confirm the items in the table below. The official enabling procedure is described in Siemens Support entry 108994400.

Step-by-Step Solution: Make the LOGO! Reachable from the Phone

1. Put the PC on Wi-Fi for a control test. Disconnect the Ethernet cable from the PC and let it join the same SSID the phone uses. Open http://<logo-ip>. If the PC now fails too, the LOGO! is on a different subnet than the Wi-Fi; the problem is purely L3 and the rest of this procedure applies. If the PC still works on Wi-Fi but the phone does not, jump to step 6 (filter / browser).
2. Reconcile the IP plan. All three devices - LOGO!, PC, phone - must share Network ID, Subnet Mask, and Default Gateway. The simplest plan is to put the LOGO! on a static IP inside the router's DHCP range only if you exclude that address from DHCP, or to put the LOGO! on a static IP outside the DHCP range but still inside the same subnet. Typical SOHO plan:

On the LOGO! onboard display, set the values via ESC > Network > IP Address / Subnet Mask / Gateway, or use LOGO! Soft Comfort: Tools > Transfer > Configure Network. The Siemens manual LOGO! 8 System Manual, 06/2021 edition, article 6ED1050-1AA08-0AA0, Section "Configuring the network settings" describes the on-device menu.

3. Exclude the LOGO! IP from the router's DHCP range. Log into the SOHO router (commonly 192.168.1.1) and either (a) narrow the DHCP pool so it does not include 192.168.1.10, or (b) create a DHCP reservation / static lease for the LOGO!'s MAC address. This stops the router from handing the LOGO!'s address to a phone or laptop.
4. Re-verify with the phone. Connect the phone to the same SSID, open a browser, navigate to http://192.168.1.10. The LOGO! Web Server page should paint. If the address bar shows Not secure, that is normal - the Web Server is plain HTTP.
5. Disable router-side isolation. On the router, confirm the following flags are off for the SSID the phone uses: AP Isolation / Client Isolation, Wireless Isolation, Guest Network mode (guest networks always block LAN access). On enterprise-style APs (Ubiquiti, TP-Link Omada, MikroTik) check WLAN > Access.
6. Disable MAC / device filters. Routers with MAC Filtering or Access Control enabled may block unknown devices. Either disable filtering or add the LOGO!'s MAC (printed on the device label and visible under ESC > Network > MAC) and the phone's MAC to the allow-list.
7. Allow plain HTTP on the phone browser. Modern Chromium-based browsers (Chrome 90+, Samsung Internet 14+, Edge mobile) display a security warning for http:// sites but still render them. Firefox mobile renders http:// without complaint. If the phone uses a corporate MDM profile or a "Safe Browsing" filter app, the request may be silently dropped - whitelist the LOGO! IP in the MDM console.
8. Test the underlying path with a ping app. Install "Network Analyzer" or "PingTools" on the phone and confirm:

   ping 192.168.1.10       // LOGO! - must succeed
   ping 192.168.1.1        // Router  - must succeed
   ping 8.8.8.8            // Internet - must succeed (proves WAN path)
   

   If the LOGO! ping fails but the router ping succeeds, the LOGO! is on a different /24, a different VLAN, or is being filtered. If both pings fail, the phone is on a guest network or a different SSID/VLAN.

Verification: Proving the Phone Can Reach the LOGO!

Configuration Reference: LOGO! Web Server Parameters

Edge Cases and Field-Proven Caveats

• 5 GHz vs 2.4 GHz. Older LOGO! 8 base modules do not transmit Wi-Fi (the module is wired Ethernet only). The phone must join the same SSID the router offers, but the LOGO! stays on the router's Ethernet port. If the router is dual-band, put the phone on the same band the PC uses for the diagnostic test.
• Two routers cascaded. A common home setup is ISP router → Wi-Fi router. The PC sits behind the Wi-Fi router, the phone sits on the Wi-Fi router, but the LOGO! is plugged into the ISP router. The PC works because the ISP router is also in the path; the phone cannot reach the LOGO! because the ISP router and the Wi-Fi router are on different subnets. Fix: put the LOGO! on the same router the phone talks to, or set the Wi-Fi router to Access Point mode.
• VPN on the phone. If the phone is connected to a corporate VPN (Cisco AnyConnect, GlobalProtect, WireGuard, etc.), all traffic may be forced through the tunnel and the LOGO! appears off-subnet. Disconnect the VPN for the test.
• IPv6-only or dual-stack routers. Some ISP routers (e.g. Fritz!Box 7590 with certain firmwares) advertise IPv6 and use a non-standard IPv4 gateway. Force the phone to obtain an IPv4 address in the Wi-Fi settings, or disable IPv6 on the router.
• Power-saving on the phone. Aggressive battery savers (Xiaomi MIUI, Huawei EMUI, Samsung Deep Sleep) may put the Wi-Fi radio to sleep. Pin the Web Server tab in the recent-apps list to keep it awake.
• HTTPS expectation. The LOGO! 8 Web Server speaks HTTP only. There is no TLS option in the firmware. A browser that auto-upgrades to HTTPS will fail. Type the URL explicitly as http://.

Troubleshooting Matrix

Related Siemens Documentation

• Siemens Support 108994400 - How do you enable and call the web server on LOGO! 8?
• LOGO! 8 System Manual (06/2021), article 6ED1050-1AA08-0AA0 - section "Web Server" and "Network settings"
• LOGO! Soft Comfort V8.3 Online Help - chapter "Configuring the Web Server"

FAQ