Ok, I am so puzzled now. I have followed the wiki page (https://openwrt.org/docs/guide-user/network/wan/wwan/3gdongle), searched for multiple hours around the internet, but I have found no working solution. I even use a powered USB hub.
I have a "XS Stick P14" Modem (1c9e:f000 when unswitched, 1c9e:9605 switched [at least on Arch Linux]). It is confirmed that is works (no hardware failure)
I am unsure whether modeswitch works fine or what causes the problem.
usbmode -s
returns:
Failed to send switch message
cat /sys/kernel/debug/usb/devices
returns:
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 1
B: Alloc= 0/800 us ( 0%), #Int= 2, #Iso= 0
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1d6b ProdID=0002 Rev= 4.09
S: Manufacturer=Linux 4.9.152 ehci_hcd
S: Product=EHCI Host Controller
S: SerialNumber=ehci-platform
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr= 0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 4
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=05e3 ProdID=0608 Rev=85.36
S: Product=USB2.0 Hub
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=256ms
T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 17 Spd=480 MxCh= 4
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=02 MxPS=64 #Cfgs= 1
P: Vendor=0424 ProdID=a700 Rev= 0.00
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr= 98mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=01 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=256ms
I:* If#= 0 Alt= 1 #EPs= 1 Cls=09(hub ) Sub=00 Prot=02 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=256ms
T: Bus=01 Lev=03 Prnt=17 Port=00 Cnt=01 Dev#= 18 Spd=480 MxCh= 0
D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=1c9e ProdID=f000 Rev= 0.00
S: Manufacturer=USB Modem
S: Product=USB Modem
S: SerialNumber=1234567890ABCDEF
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=500mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=(none)
E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
If I see that correctly, that means that usb mode switch has switched the mode successfully, but the the USB product id didn't change. HOWEVER, there is no /dev/ttyUSB* created.
dmesg
only returns:
[ 1892.721119] usb 1-1.1.1: new high-speed USB device number 19 using ehci-platform
I have even seen the USB modem blink purple (that means that it is trying to connect to an edge network) when there was no /dev/ttyUSB
lsmod
returns:
root@OpenWrt:~# lsmod
ath 16832 3 ath9k,ath9k_common,ath9k_hw
ath9k 90992 0
ath9k_common 10880 1 ath9k
ath9k_hw 331808 2 ath9k,ath9k_common
cdc_ether 4032 1 rndis_host
cfg80211 200528 4 ath9k,ath9k_common,ath,mac80211
compat 4704 4 ath9k,ath9k_common,mac80211,cfg80211
crc_ccitt 960 1 ppp_async
ehci_hcd 33040 1 ehci_platform
ehci_platform 3968 0
gpio_button_hotplug 4544 0
ip_tables 10064 4 iptable_nat,iptable_mangle,iptable_filter
ip6_tables 9920 24 ip6table_mangle,ip6table_filter
ip6_udp_tunnel 1376 1 wireguard
ip6t_REJECT 896 2
ip6table_filter 608 1
ip6table_mangle 1120 1
ipt_MASQUERADE 608 2
ipt_REJECT 864 2
iptable_filter 672 1
iptable_mangle 896 1
iptable_nat 704 1
ledtrig_usbport 2160 0
mac80211 392224 1 ath9k
mii 3296 1 usbnet
nf_conntrack 52320 9 nf_conntrack_ipv6,xt_state,xt_conntrack,xt_CT,nf_nat_masquerade_ipv4,nf_conntrack_ipv4,nf_nat_ipv4,nf_nat,nf_conntrack_rtcache
nf_conntrack_ipv4 5280 19
nf_conntrack_ipv6 5792 10
nf_conntrack_rtcache 2432 0
nf_defrag_ipv4 800 1 nf_conntrack_ipv4
nf_defrag_ipv6 4240 1 nf_conntrack_ipv6
nf_log_common 2336 2 nf_log_ipv4,nf_log_ipv6
nf_log_ipv4 3104 0
nf_log_ipv6 3264 0
nf_nat 9456 4 xt_nat,nf_nat_redirect,nf_nat_masquerade_ipv4,nf_nat_ipv4
nf_nat_ipv4 3760 1 iptable_nat
nf_nat_masquerade_ipv4 1264 1 ipt_MASQUERADE
nf_nat_redirect 864 1 xt_REDIRECT
nf_reject_ipv4 2080 1 ipt_REJECT
nf_reject_ipv6 2304 1 ip6t_REJECT
nls_base 4736 1 usbcore
option 30848 0
ppp_async 6176 0
ppp_generic 21008 3 pppoe,ppp_async,pppox
pppoe 7808 0
pppox 1168 1 pppoe
rndis_host 4768 0
slhc 4160 1 ppp_generic
udp_tunnel 2176 1 wireguard
uhci_hcd 18672 0
usb_common 1312 1 usbcore
usb_wwan 4128 1 option
usbcore 118944 10 option,usb_wwan,rndis_host,cdc_ether,usbserial,usbnet,uhci_hcd,ledtrig_usbport,ehci_platform,ehci_hcd
usbnet 15536 2 rndis_host,cdc_ether
usbserial 16864 2 option,usb_wwan
wireguard 125152 0
x_tables 11344 23 ipt_REJECT,ipt_MASQUERADE,xt_time,xt_tcpudp,xt_state,xt_nat,xt_multiport,xt_mark,xt_mac,xt_limit,xt_conntrack,xt_comment,xt_TCPMSS,xt_REDIRECT,xt_LOG,xt_CT,iptable_mangle,iptable_filter,ip_tables,ip6t_REJECT,ip6table_mangle,ip6table_filter,ip6_tables
xt_CT 2496 0
xt_LOG 704 0
xt_REDIRECT 608 0
xt_TCPMSS 2624 2
xt_comment 448196
xt_conntrack 2144 28
xt_limit 960 20
xt_mac 576 0
xt_mark 608 0
xt_multiport 1152 0
xt_nat 1088 0
xt_state 640 0
xt_tcpudp 1664 10
xt_time 1568 0