No LTE Link on cAP LTE12 ax and Deutsche Telekom (cAPGi-5HaxD2HaxD&EG12-EA)

RouterOS Wireless Networking
1

Hello everyone.

I am having problems setting up an LTE link with my cAP LTE12 ax. I am using a SIM card from Deutsche Telekom (26201), which works perfectly in my LtAP Mini (2024).

I have already tried all possible tips from the forum, like disabling “Use Network APN”, unfortunately without success. On the LtAP Mini, even the default config is working out of the box with this card.

MikroTik device: cAPGi-5HaxD2HaxD&EG12-EA
RouterOS version: 7.19.3 and 7.20Beta5
Modem firmware: EG12EAPAR01A15M4G_01.203.01.203

Debug log:

 2025-07-14 17:15:36 lte,debug lte mbim: state: searching => radio off
 2025-07-14 17:15:36 lte,debug lte mbim: set radio: off
 2025-07-14 17:15:36 lte,debug lte mbim: <<< S #9402 - connect: radio state
 2025-07-14 17:15:36 lte,debug lte mbim: >>> N #0 - connect: radio state
 2025-07-14 17:15:36 lte,debug lte mbim: >>> D #9402 - connect: radio state
 2025-07-14 17:15:36 lte,debug lte mbim: state: radio off => offline
 2025-07-14 17:15:36 lte,debug lte mbim: state: offline => starting
 2025-07-14 17:15:36 lte,debug lte mbim: <<< Q #9403 - connect: subscriber ready status
 2025-07-14 17:15:36 lte,debug lte mbim: >>> N #0 - connect: register state
 2025-07-14 17:15:36 lte,debug lte mbim: >>> N #0 - connect: register state
 2025-07-14 17:15:36 lte,debug lte mbim: >>> N #0 - sms: configuration
 2025-07-14 17:15:36 lte,debug lte mbim: sms service center +491710760000
 2025-07-14 17:15:36 lte,debug lte mbim: >>> D #9403 - connect: subscriber ready status
 2025-07-14 17:15:36 lte,debug lte mbim: subscriber ready state: initialized
 2025-07-14 17:15:36 lte,debug lte mbim: state: starting => sim ready
 2025-07-14 17:15:36 lte,debug lte mbim: <<< Q #9404 - conn_ext: lte attach config
 2025-07-14 17:15:36 lte,debug lte mbim: >>> D #9404 - conn_ext: lte attach config
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 0 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 1 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 2 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: set lte attach apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: <<< S #9405 - conn_ext: lte attach config
 2025-07-14 17:15:36 lte,debug lte mbim: >>> D #9405 - conn_ext: lte attach config
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 0 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 1 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: lte attach ctx  source: 3 roam: 2 ip: 0 apn: internet.telekom
 2025-07-14 17:15:36 lte,debug lte mbim: request register, operator: [auto]
 2025-07-14 17:15:36 lte,debug lte mbim: <<< S #9406 - connect: register state
 2025-07-14 17:15:37 lte,debug lte mbim: >>> D #9406 - connect: register state
 2025-07-14 17:15:37 lte,debug lte mbim: register state: deregistered
 2025-07-14 17:15:37 lte,debug lte mbim: state: sim ready => deregistered
 2025-07-14 17:15:37 lte,debug lte mbim: set radio: on
 2025-07-14 17:15:37 lte,debug lte mbim: <<< S #9407 - connect: radio state
 2025-07-14 17:15:37 lte,debug lte mbim: >>> N #0 - connect: radio state
 2025-07-14 17:15:37 lte,debug lte mbim: >>> D #9407 - connect: radio state
 2025-07-14 17:15:37 lte,debug lte mbim: >>> N #0 - connect: register state
 2025-07-14 17:15:37 lte,debug lte mbim: register state: searching
 2025-07-14 17:15:37 lte,debug lte mbim: state: deregistered => searching
 2025-07-14 17:15:37 lte,debug lte mbim: >>> N #0 - sms: configuration
 2025-07-14 17:15:37 lte,debug lte mbim: sms service center +491710760000
 2025-07-14 17:17:36 lte,error lte forced reconfiguration due to difficulty setting link up

Any ideas?

2

Might be useful to show actual config ?
Minus serial, passwds, …

3

Answer from a chatbot(I suggest others to use it as well, since Mikrotik is scriptable and it plays nicely):

Based on the debug log and the information you’ve provided, the modem in your cAP LTE12 ax is struggling to register on the Deutsche Telekom network. The log shows it’s searching but then gets deregistered and times out.

Here are a few things you can check and try:

  1. Check Network Registration and Signal Strength:
    Even if the antenna is connected, it’s good to verify the signal quality. You can check the cellular signal strength details by running the following command in the MikroTik terminal:

    /interface lte info lte1 once

    Look for values like RSRP, RSRQ, and SINR. A weak signal could be the reason for the registration failure. For a stable 4G/LTE connection, you’d ideally want to see an RSRP of -100 dBm or better (e.g., -95 dBm, -85 dBm).

  2. Set the APN Manually:
    You mentioned you tried disabling “Use Network APN”. Let’s ensure the APN is explicitly set. Create a new LTE APN profile and apply it to the interface.

    /interface lte apn
add name=telekom apn=internet.telekom
/interface lte
set lte1 apn-profiles=telekom

    For some business contracts with Deutsche Telekom, the APN might be different (e.g., internet.v6.telekom or a custom one). It might be worth double-checking if your SIM has a specific APN requirement.

  3. Lock Bands:
    Sometimes, modems struggle to pick the best band and get stuck. The LtAP Mini might have a different modem that handles this better. You can try to manually specify the bands that Deutsche Telekom uses. Common LTE bands for DT in Germany are 3, 7, and 20.

    You can set the bands using this command:

    /interface lte
set lte1 bands=3,7,20

    After setting the bands, it’s a good idea to reboot the router or restart the LTE interface.

I’d recommend starting with checking the signal strength and then trying to lock the bands, as these are common culprits for network registration issues.

4

Just for reference, replacement device works as expected after restoring the backup i've created on the broken device.