Based on the logs, it appears that there are continuous modem timeouts, leading to the unavailability of modem details, including cellular information. So it is hard to say what causes this.
Could you please check if you have enabled roaming? You can find this option in Network -> Mobile -> General.
Does your phone work fine with this SIM while you are roaming? If so, can you check the APN settings on your phone when you use this SIM? Then, try configuring the router to use the same APN.
Your operator may provide a specific APN for roaming. APN can be configured in Network -> Interfaces -> Edit mob1s1a1 (SIM1). There, you can disable auto APN and enter your custom APN.
Have you tried using a second SIM slot?
Also, have you tried a different SIM card, preferably from a different operator, to see if it works?