В общем все равно связь пропадает после запуска проверки скорости или при начале скачивания файлов примерно более 50Мб.
Очистил журнал, запустил проверку скорости через яндекс связь пропала, а потом восстановилась. Вот логи:
[I] Dec 11 17:50:05 ndm: Core::Syslog: the system log has been cleared.
[I] Dec 11 17:50:25 kernel: usb 1-1: USB disconnect, device number 91
[I] Dec 11 17:50:25 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[I] Dec 11 17:50:25 kernel: cdc_ncm 1-1:1.6 eth0: unregister 'cdc_ncm' usb-ehci-platform-1, CDC NCM
[I] Dec 11 17:50:25 ndm: Network::Interface::Usb: "UsbLte0": interface "UsbLte0" is unplugged.
[E] Dec 11 17:50:25 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:25 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[I] Dec 11 17:50:25 ndm: Network::Interface::Base: "UsbLte0": "ip" changed "ipv4" layer state "running" to "disabled".
[I] Dec 11 17:50:25 ndm: Network::Interface::Ip: "UsbLte0": IP address cleared.
[E] Dec 11 17:50:26 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:26 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:27 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:27 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:28 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:28 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:29 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:29 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:29 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:29 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:30 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:30 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:31 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:31 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[E] Dec 11 17:50:32 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:32 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[I] Dec 11 17:50:33 kernel: cdc_ncm 1-1:1.8 eth1: unregister 'cdc_ncm' usb-ehci-platform-1, CDC NCM
[I] Dec 11 17:50:33 kernel: cdc_ncm 1-1:1.10 eth3: unregister 'cdc_ncm' usb-ehci-platform-1, CDC NCM
[I] Dec 11 17:50:33 ndm: Network::Interface::Base: "UsbLte0": "usb" changed "link" layer state "running" to "detached".
[E] Dec 11 17:50:33 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:33 ndm: Mobile::TtyDevice: "UsbLte0": tty0 disconnected.
[I] Dec 11 17:50:33 kernel: usb 1-1: new high-speed USB device number 92 using ehci-platform
[I] Dec 11 17:50:34 kernel: usb 1-1: New USB device found, idVendor=8087, idProduct=095a, bcdDevice= 3.33
[I] Dec 11 17:50:34 kernel: usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[I] Dec 11 17:50:34 kernel: usb 1-1: Product: MODEM + 2 CDC-ACM + 3 CDC-NCM + SS
[I] Dec 11 17:50:34 kernel: usb 1-1: Manufacturer: Intel Corp.
[I] Dec 11 17:50:34 kernel: usb 1-1: SerialNumber: 004999010640000
[I] Dec 11 17:50:34 kernel: cdc_acm 1-1:1.0: ttyACM1: USB ACM device
[I] Dec 11 17:50:34 kernel: cdc_acm 1-1:1.2: ttyACM2: USB ACM device
[I] Dec 11 17:50:34 kernel: cdc_acm 1-1:1.4: ttyACM3: USB ACM device
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.6: MAC-Address: 00:00:11:12:13:14
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.6: setting rx_max = 16384
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.6 eth0: register 'cdc_ncm' at usb-ehci-platform-1, CDC NCM, 00:00:11:12:13:14
[I] Dec 11 17:50:34 ndm: Network::Interface::Ip: "UsbLte0": IP address cleared.
[I] Dec 11 17:50:34 ndm: Network::Interface::Ip: "UsbLte0": removing default route via UsbLte0.
[E] Dec 11 17:50:34 ndm: Io::Serial: unable to write data: input/output error.
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.8: MAC-Address: 00:00:11:12:13:16
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.8: setting rx_max = 16384
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.8 eth1: register 'cdc_ncm' at usb-ehci-platform-1, CDC NCM, 00:00:11:12:13:16
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.10: MAC-Address: 00:00:11:12:13:18
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.10: setting rx_max = 16384
[I] Dec 11 17:50:34 kernel: cdc_ncm 1-1:1.10 eth3: register 'cdc_ncm' at usb-ehci-platform-1, CDC NCM, 00:00:11:12:13:18
[I] Dec 11 17:50:34 kernel: IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[I] Dec 11 17:50:34 ndm: Network::Interface::Usb: "UsbLte0": interface "UsbLte0" is plugged (port 1).
[I] Dec 11 17:50:34 ndm: Network::InternetChecker: Internet access lost (status: 0x0000).
[I] Dec 11 17:50:35 ndm: Http::Nginx: loaded SSL certificate for "41fb77f669b9bf33b1b2d88b.keenetic.io".
[I] Dec 11 17:50:35 ndm: Core::Server: started Session /var/run/ndm.core.socket.
[I] Dec 11 17:50:35 ndm: Core::Session: client disconnected.
[I] Dec 11 17:50:35 ndm: Http::Manager: updated configuration.
[I] Dec 11 17:50:35 ndm: Core::Server: started Session /var/run/ndm.core.socket.
[I] Dec 11 17:50:35 ndm: Core::Session: client disconnected.
[I] Dec 11 17:50:37 ndm: Mobile::Mvno: "UsbLte0": matched 25001, APN: "internet.mts.ru".
[I] Dec 11 17:50:46 ndm: UsbLte::Connection: "UsbLte0": connection initialized.
[I] Dec 11 17:50:46 kernel: cdc_ncm 1-1:1.6 eth0: 480 mbit/s downlink 480 mbit/s uplink
[I] Dec 11 17:50:46 ndm: UsbLte::Connection: "UsbLte0": network ready.
[I] Dec 11 17:50:46 kernel: IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[I] Dec 11 17:50:48 ndm: Network::Interface::Base: "UsbLte0": "ethernet" changed "link" layer state "pending" to "running".
[I] Dec 11 17:50:48 ndm: UsbLte::Connection: "UsbLte0": connection established.
[I] Dec 11 17:50:49 ndm: Network::Interface::Base: "UsbLte0": "ip" changed "ipv4" layer state "disabled" to "running".
[I] Dec 11 17:50:49 ndm: Network::Interface::Ip: "UsbLte0": IP address is 10.104.186.148/32.
[I] Dec 11 17:50:49 ndm: Network::Interface::Ip: "UsbLte0": interface "UsbLte0" is global, priority 33117.
[I] Dec 11 17:50:49 ndm: Network::Interface::Ip: "UsbLte0": adding default route via UsbLte0.
[I] Dec 11 17:50:49 ndm: Dns::InterfaceSpecific: adding name server 217.66.153.254.
[I] Dec 11 17:50:49 ndm: Dns::InterfaceSpecific: "UsbLte0": name server 217.66.153.254 added, domain (default).
[I] Dec 11 17:50:49 ndm: Dns::InterfaceSpecific: adding name server 217.66.153.250.
[I] Dec 11 17:50:49 ndm: Dns::InterfaceSpecific: "UsbLte0": name server 217.66.153.250 added, domain (default).
[I] Dec 11 17:50:49 ndm: Network::InterfaceFlusher: flushed IPv4 UsbLte0 conntrack and route cache.
[I] Dec 11 17:50:50 ndm: Http::Nginx: loaded SSL certificate for "41fb77f669b9bf33b1b2d88b.keenetic.io".
[I] Dec 11 17:50:50 ndm: Core::Server: started Session /var/run/ndm.core.socket.
[I] Dec 11 17:50:50 ndm: Core::Session: client disconnected.
[I] Dec 11 17:50:51 ndm: Http::Manager: updated configuration.
[I] Dec 11 17:50:51 ndm: Core::Server: started Session /var/run/ndm.core.socket.
[I] Dec 11 17:50:51 ndm: Core::Session: client disconnected.
[I] Dec 11 17:50:54 ndm: Network::InternetChecker: Internet access detected.
Может ли проблема быть на стороне провайдера (МТС)? Или проблема в настройках роутера, или модема?