Problem solved (part)!
After changing to another USB hub the modem is working reliably for now, without errors. The working model is HAMA 78472 USB 2.0 HUB 1:4.
The other thing I found is that the modem will refuse to send a message if it contains some localized characters (čćšđž). Doesn't matter if it is only one character in the message or up to 70, if a single special character is in it won't send it. Edit: that's how it is configured at the beginning of the user.sms.lua script.
I'm actively searching for a solution, but at least it works now.
After changing to another USB hub the modem is working reliably for now, without errors. The working model is HAMA 78472 USB 2.0 HUB 1:4.
Code:
May 22 19:30:26 homeLYnk user.notice usb-modeswitch: 1-1.4:1.5: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:25 homeLYnk user.notice usb-modeswitch: 1-1.4:1.4: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:25 homeLYnk user.notice usb-modeswitch: 1-1.4:1.3: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:25 homeLYnk user.notice usb-modeswitch: 1-1.4:1.2: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:24 homeLYnk user.notice usb-modeswitch: 1-1.4:1.1: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:24 homeLYnk user.notice usb-modeswitch: 1-1.4:1.0: Manufacturer=HUAWEI Product=HUAWEI_Mobile Serial=?
May 22 19:30:24 homeLYnk user.notice usb-modeswitch: 1-1:1.0: Manufacturer=? Product=USB_2.0_Hub Serial=?
May 22 19:30:23 homeLYnk kern.notice kernel: [ 861.445516] sd 13:0:0:0: [sda] Attached SCSI removable disk
May 22 19:30:23 homeLYnk kern.notice kernel: [ 861.431609] scsi 13:0:0:0: Direct-Access HUAWEI SD Storage 2.31 PQ: 0 ANSI: 2
May 22 19:30:23 homeLYnk kern.notice kernel: [ 861.425653] scsi 12:0:0:0: CD-ROM HUAWEI Mass Storage 2.31 PQ: 0 ANSI: 2
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.424813] scsi13 : usb-storage 1-1.4:1.5
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.424229] usb-storage 1-1.4:1.5: USB Mass Storage device detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.419922] scsi12 : usb-storage 1-1.4:1.4
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.419368] usb-storage 1-1.4:1.4: USB Mass Storage device detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.418014] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB2
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.415026] option 1-1.4:1.3: GSM modem (1-port) converter detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.413376] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB1
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.410076] option 1-1.4:1.2: GSM modem (1-port) converter detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.406802] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB0
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.403886] option 1-1.4:1.0: GSM modem (1-port) converter detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.397314] usb 1-1.4: Manufacturer: HUAWEI
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.397283] usb 1-1.4: Product: HUAWEI Mobile
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.397243] usb 1-1.4: New USB device strings: Mfr=3, Product=2, SerialNumber=0
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.397173] usb 1-1.4: New USB device found, idVendor=12d1, idProduct=1506
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.392167] usb 1-1.4: not running at top speed; connect to a high speed hub
May 22 19:30:22 homeLYnk kern.info kernel: [ 860.287213] usb 1-1.4: new full-speed USB device number 17 using ci_hdrc
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.992616] hub 1-1:1.0: 4 ports detected
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.990046] hub 1-1:1.0: USB hub found
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.987330] usb 1-1: Product: USB 2.0 Hub
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.987289] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.987220] usb 1-1: New USB device found, idVendor=1a40, idProduct=0101
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.983180] usb 1-1: not running at top speed; connect to a high speed hub
May 22 19:30:22 homeLYnk kern.info kernel: [ 859.850658] usb 1-1: new full-speed USB device number 16 using ci_hdrcThe other thing I found is that the modem will refuse to send a message if it contains some localized characters (čćšđž). Doesn't matter if it is only one character in the message or up to 70, if a single special character is in it won't send it. Edit: that's how it is configured at the beginning of the user.sms.lua script.
I'm actively searching for a solution, but at least it works now.