Breaking ssh connections through UPC Wireless Gateway 5.01

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  • Level 7  
    Dear Sir or Madam

    I don't really know which side to get to the problem with the network I have.

    From a laptop (actually two business and private) connect to the network at work using OpenVPN. After logging in via OpenVPN, log in to the server using SSH and Putty software. Everything works perfectly in many places (hotels, airports, even the simplest internet in the family) except for one place: an attempt to connect from me from home. Symptoms are that I can log in via ssh, I can even partially work until I want to write something larger to the terminal with an ssh connection, for example running mc or trying to view a large file using the less command (several thousand lines). At this point the terminal freezes and the fun ends. I suspect that the problem concerns my home network (it does not occur anywhere else, after moving the computer to another network, the problem disappears, server logs at work do not show the slightest trace of problems). To make it happier, at the same time I can normally use the internet, display websites, watch a video on youtube, etc. The problem concerns the Wi-Fi connection (checked repeatedly) but the connection via a regular network cable did not improve the situation.

    Now a handful of information about the network: Wireless Gateway modem from UPC with a firewall enabled (disabling it does not solve the problem), MTU size is the highest from the available range 1280-1500 (I guess in bytes, but I'm not sure, the change does not affect problem). Logs from hardware do not contain entries from the period of problems. Configuration data below (unfortunately the device does not allow changes, but maybe something will prompt).

    Compliance with standards: DOCSIS 3.0
    Hardware version: 5.01
    Software version: CH7465LG-NCIP-
    Cable interface MAC address: AC: 22: 05: 39: 82: B4
    Modem serial number: DEAP710217F5
    Device operation time: 4day (s) 4h: 23m: 41s
    Network access: Allowed

    Network access Allowed
    Maximum CPE number 2
    Baseline Privacy Enabled
    DOCSIS mode DOCSIS 3.0
    Configuration file fiberpower60_062013_v6.cfg

    Basic downstream
    SFID 684548130
    Max Traffic Rate 10700000 bps
    Max Traffic Burst 16320 bytes
    Min Traffic Rate 0 bps
    SFID 684548129
    Max Traffic Rate 60720,000 bps
    Max Traffic Burst 42600 bytes
    Min Traffic Rate 0 bps

    Basic upstream channel
    SFID 684539939
    Max Traffic Rate 1070000 bps
    Max Traffic Burst 16320 bytes
    Min Traffic Rate 0 bps
    Max Concatenated Burst 16320 bytes
    Best Effort queuing type
    SFID 684539936
    Max Traffic Rate 6072000 bps
    Max Traffic Burst 42600 bytes
    Min Traffic Rate 0 bps
    Max Concatenated Burst 42600 bytes
    Best Effort queuing type
  • Helpful post
    Network and Internet specialist
    Something about MTU smells like a problem.
    google openvpn MTU

    BTW: I recommend screen under linux, "man screen", this will allow you to start a session in ssh after logging in again in the place where something broke. for example,

    screen -e ^^^
  • Level 7  
    Thank you for the quick reply. I used the procedure described on the given page. It looks like the problem is gone. I will try tomorrow to do some more tests, if the problem returns I will still ask.