since September 2021 we are having connection issues with the following modem types: EM7455, EM7421
To be more specific they are apperently unable or unwilling to use CHAP as an authentication method.
EM7455 - it seems like 30% of our modems have this issue - the newer the device - the more likely the issue is.
EM7421 100% of our modems have this issue.
We are using Windows 10 Fujitsu Notebooks - drivers and firmware are up to date and the configuration of all notebooks is 100% identical.
The Notebook models are alle from Fujitsu: T938, U729, U759, U7510, U7511
In total we use roughly 1400 devices
Now to the interesting part: we can switch the modems and it will solve the problem → so we don’t think its an issue with windows, the configuration or the Software we use.
To be more specific, if we find a “working” EM7455, we can switch it with a “non working” one and it will fix the device. So it seems to be a Modem issue. They don’t seem to be deffective either, since they work with a different SIM (thats not using CHAP).
It feels like a change in some of the device, like a new revision of the hardware. This would explain why EM7421 won’t work at all. Futhermore oder model modems, do work at 100% - the EM7305 for example.
We tried different firmware versions, drivers and also different Windows Version - without any success.
I hope you have some suggestion or input.
Thank you very much for your time and feedback.