Problem
The Teltonika router establishes a mobile data connection using the inserted SIM card, allowing data transmission. However, the mobile data connection is regularly disconnected after about two hours, so data transmission is no longer possible. The automatic monitoring of the mobile data connection (Ping-Reboot) detects this data transmission fault and triggers a router restart after approximately 15 minutes. The mobile data connection is then restored, and data transmission is initially possible again. However, after about two hours, another disconnection occurs.
Here is an example of the event logs (System -> Maintenance -> Events Log) of an affected router in the event of an error:
Cause
The cause is likely an incompatibility with older RutOS7 firmware versions regarding VoLTE/IMS in specific configurations and mobile networks. The problem particularly occurs when the APN, username, and password are manually set in the router’s mobile network settings, as is required, for example, with Wireless Logic mdex SIM cards. When the "Auto APN" setting is used, connection interruptions often do not occur.
Solution
In firmware versions R_00.07.15 and R_00.07.16, corresponding optimisations were implemented to ensure a stable mobile data connection. Based on our experience, after the firmware update, the mobile data connection on the affected mobile routers was established stably without repeated interruptions.
Please update the affected Teltonika router to firmware version R_00.07.16 or higher. Further information can be found under Update the router/modem firmware of a Teltonika router.
Important Notice Regarding the Use of 'DMZ'
If a forwarding of all ports and protocols to a target device has been configured under Network -> Firewall -> DMZ, the router will automatically create several additional port forwarding rules to ensure that certain services and functions of the router remain accessible.
| dmz_http | Required for HTTP remote access (rule is automatically activated when necessary) |
| dmz_https | Required for HTTPS remote access (rule is automatically activated when necessary) |
| dmz_snmp | Required for SNMP remote access (rule is automatically activated when necessary) |
| dmz_ssh | Required for SSH remote access (rule is automatically activated when necessary) |
| dmz_dhcp | Necessary as a remedial measure to prevent regular interruptions of the mobile data connection. This rule should be enabled if available. |
The rule 'dmz_fw' facilitates the forwarding of all ports and protocols to a target device. If any port forwarding rules are positioned after the 'dmz_fw' rule, these will no longer be executed.
In particular, the 'dmz_dhcp' rule serves as a measure to prevent frequent disconnections and must always be enabled when using DMZ. Therefore, it is essential that the 'dmz_fw' rule is executed last and that the other rules, such as 'dmz_dhcp', are placed above it: