After trying for 3 days now to solve the problem myself, I turn to you in the hope that someone can help me.
In 2021 i bought the x750 Sptitz, and since the beginning i had some random “connection” failures from time to time.
The error is always the same (i have set up the right APN):
SIM card cannot be registered. Please check: 1. You are using the compatible modem for your carrier; 2. Whether a specific APN or data plan is required.
Mostly, a modem-reset would help, but sometimes i have to reboot the whole router.
2 days ago, suddenly internet speed/rate dropped to a sub-idrian level (200-300kb/s)
and the aforementioned dropouts now occurred every few minutes (“SIM card cannot be registered”).
I tried changing bands (as i am in germany, i tried 1, 3, 7, 8, 20, 28), which did not help.
By doing this, i also noticed that carrier aggregation does not work (AT command for CA result is “OK”)
In the night from yesterday to today, the speed suddenly improved a bit on its own:
Opening the control panel, i noticed a “frozen” modem interface (“cell info” is empty, and the “AT-command” is lacking ttyUSB2; so no commands are executable):
Also the main interface showed the simcard error again, although the internet was working.
So i did a router reboot, which destroyed the improved speed again:
On “Cell Info” all values except rsrq are “excellent” - rsrq remains at 12-14 / fair to poor, no matter where i position the router. currently it stands directly in the middle in front of the window pane, from where I can see the top of the cell tower:
(cellid redacted for privacy)
my firmware ist up to date: 3.215
In the beginning the errors were still bearable, with a modem reset/router reboot every few days, but slowly it really starts to annoy the sh*t out of me.
I hope someone can help me, I’m starting to go insane. Thank you in advance.