--- title: "Establishing an Internet Connection via an LTE Router - icom OS Routers" slug: "establishing-an-internet-connection-via-an-lte-router-en" updated: 2026-08-21T11:34:54Z published: 2026-08-21T11:34:54Z canonical: "docs.insys-icom.com/establishing-an-internet-connection-via-an-lte-router-en" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.insys-icom.com/llms.txt > Use this file to discover all available pages before exploring further. # Establishing an Internet Connection via an LTE Router - icom OS Routers This Configuration Guide shows how to configure an LTE connection manually. ## Situation A local network is to be connected to the Internet via the LTE router manually. ![cg internet via lte v2](https://docs.insys-icom.de/assets/cg_internet_via_lte_v2.png) ## Solution The steps executed in the Startup wizard for configuring a cellular connection are carried out manually for this purpose. It is prerequisite that the device has an LTE modem and a functional SIM card is inserted. This Configuration Guide assumes a device in default settings. In case of already configured devices or other network configuration requirements, the individual steps may need to be adapted. > [!NOTE] > Please note! > > The device can only be accessed via the first Ethernet socket in default settings. This avoids to bridge several networks accidentally on an already configured router when resetting to default settings. > [!NOTE] > Please note for possible differences in the naming of the cellular interface! > > The cellular interfaces have been renamed from `lteX` to `cellularX` with version **icom OS 10.0**. Depending on the version, the following description may therefore differ from your router. For security reasons, we recommend that [you regularly update your router](/kb/docs/updating-a-router-manually-en) to the latest version anyway. See [FAQ](/kb/docs/how-does-the-renaming-of-the-cellular-interface-from-ltex-to-cellularx-affect-my) for more information. 1. Open the user interface of the router: [https://insys.icom](https://insys.icom) 2. Click *To manual configuration* on the splash screen under **Manual configuration** when the splash screen appears or enter your credentials if the router is no longer in factory settings. 3. Open the ![ethernet](https://docs.insys-icom.de/assets/icons/ethernet.png) *Ports* → *Ethernet* page and get an overview of the configuration of the Ethernet ports; adjust them with a click on in the row of this port, if necessary. > [!NOTE] > The switch ports must first be assigned to an interface! > > In this case, interface **net1** remains a separate network that serves for accessing and configuring the router only. Interface **net2** is intended for connecting the devices, which are connected to the router, to the Internet. The router and its web interface can be accessed from both, **net1** and **net2**, in this example. ![cg en m3 internet via lte 01](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_01.png) 4. Open the *Network* → *Interfaces* page and get an overview of the configuration of the network interfaces; adjust them with a click on in in the row of this network interface, if necessary. ![cg en m3 internet via lte 02](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_02.png) 5. Click on the *Network* → *Interfaces* page in the *LTE* table on in the row of the network **cellular2**. 6. Enter the PIN and APN. > [!NOTE] > Please note! > > Routers with two SIM card slots do also have a second LTE interface **cellular2_2**. For routers with several slots for plug-in cards (MRcards), the LTE card can also be inserted in a slot other than slot 2; in this case, the interface is then called **cellular3** for slot 3, for example. > > The APN (Access Point Name) is important. If no or a wrong APN is configured, it may happen that no or only a 3G connection will be established. It is possible that the modem must authenticate with the provider using a user name and password. For this, click on *to extended view* at the top right. ![cg en m3 internet via lte 03](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_03.png) 7. Click on SUBMIT. 8. Click on the *Network* → *Interfaces* page in the *IP networks* table on in the row of the network **net2** and check the checkbox *Active*. 9. Click on behind *Static IP addresses* and enter the *IP address* with *Netmask* the router is supposed to get in the LAN. > [!NOTE] > Please note! > > The operating mode **Local - always started** means that the interface is started when the router is started. Several static IPv4 and IPv6 addresses can be configured for this interface. ![cg en m3 internet via lte 04](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_04.png) 10. Click on SUBMIT. 11. Click on on the *Network* → *WAN / Internet* page to add a WAN chain. > [!NOTE] > Please note! > > The interfaces are arranged one after another in a WAN chain. It will be tried to put the interfaces in the WAN chain in **online** condition one after another. Each interface can optionally be provided with a connection check that confirms the **online** condition. If the connection check fails or the router self-service detects that an interface in a WAN chain does not have the **online** condition any longer, the establishment of the WAN chain will be considered as failed. 12. Click on behind *Interfaces in WAN chain* to add an interface to this WAN chain and select the *Interface* **cellular2**. > [!NOTE] > Please note! > > In case of one interface in a WAN chain, the router usually detects independently whether it is in online condition or not. In case the interface is **offline**, you can select whether the own WAN chain, another WAN chain (if available) or only the interface itself should be restarted. An additional connection check may still be reasonable. In case of Ethernet interfaces, the Ethernet link is not sufficient to detect whether IP traffic is possible. A DNS check or a ping to a certain IP address provides more certainty about the possibility to reach certain destinations. An Internet connection via LTE can also be useless if DNS resolution does not work any longer. In such cases, it might be reasonable to change the WAN chain and establish the Internet connection via another medium or restart the existing interfaces. ![cg en m3 internet via lte 05](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_05.png) 13. Click on SUBMIT. 14. Click on hinter *Static routes* on the *Network* → *Routing* page to add a static route: - Creation after start of *Interface*: cellular2 - *Type of the route*: Default route - *Gateway*: dynamic - use received IP address > [!NOTE] > Please note! > > When starting an interface (local or in a WAN chain), it will always be checked, whether a route is configured for this interface. The type of the route can be a default route (0.0.0.0/0), a network route (e.g. into network 172.16.0.0/16) or a host route (e.g. 172.16.7.4/16). The gateway to which the new route shall direct, will be received dynamically in this case. A static IP address is known for a few providers only. Alternatively, it would be possible to enter the interface **cellular2** as gateway for the route in case of an LTE modem. An IP packet will be sent via the route, whose netmask is most strict, thus /32 for IPv4 and /128 for IPv6). The priority of the route defines which route is to be used if several routes with identical range are present. The lowest priority figure defines the route that is to be used first. This allows to add several default routes together. ![cg en m3 internet via lte 06](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_06.png) 15. Click on SUBMIT. 16. Click on behind *Source NAT* on the *Network* → *Firewall / NAT* page to add a Source NAT rule: - *Type*: Masquerade - Protocol: All - *Output interface*: cellular2 > [!NOTE] > Please note! > > Most providers allot private IP addresses to the modems connecting to the network since there are no sufficient free public IPv4 addresses any more. In order that IP packets that are sent from the LAN to the Internet find their way back from the Internet to the right LAN again, the router must replace the source IPv4 address with the IP address that the modem has received from the provider dynamically. This process is called masquerading. This is necessary if the provider assigns public accessible IP addresses. It is absolutely important to activate the IP filters in this case to regulate the permitted IP traffic. ![cg en m3 internet via lte 07](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_07.png) 17. Click on SUBMIT. 18. If your router is still in default settings: Open the *Administration* → *User* page and click on in the row of the user to configure the standard user and enter a *User name* and a *Passwort*. ![cg en m3 internet via lte 08](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_08.png) 19. Click on SUBMIT. 20. Click on ACTIVATE PROFILE to activate a profile. ## Result testing 1. Open the ![view dashboard outline](https://docs.insys-icom.de/assets/icons/view-dashboard-outline.png) *Status* → *Dashboard* page, check the settings of the local networks and observe the establishment of the LTE Connection and the WAN chain. ![cg en m3 internet via lte 09](https://docs.insys-icom.de/assets/cg_en_m3_internet_via_lte_09.png) ## Troubleshooting - The status of the WAN chain and their interfaces is displayed on the ![view dashboard outline](https://docs.insys-icom.de/assets/icons/view-dashboard-outline.png) *Status* → *Dashboard* page. If an interface does not achieve the **online** condition, its condition can also be examined on this page. - If no network traffic is achieved, the tools integrated in the router can be used for [debugging](/kb/docs/debugging-en). - Network devices connected to the router cannot use the Internet connection. The reason can be that they have not entered the router as gateway and DNS server. - The IP filters can be deactivated for testing purposes. The router itself is also subject to the IP filters. If the router itself has to send packets, an OUTPUT rule is necessary for this. If the router itself has to receive packets, an INPUT rule is necessary for this. In order to be able to route IP packets, a FORWARD rule is necessary. Standard IP address: https://192.168.1.1; login depending on configuration; default for earlier firmware versions: *User name*: **insys**, *Password*: **icom** Activating a profile means that the profile becomes the running profile