I have a strange issue with network performance. After I boot the Ubuntu 15.04 and use it for some time, the network starts to work extremely slow — 7 Mb download instead of 70-100, upload is almost not working (tested via speedtest.net). Ping also increases from standard 3ms to 70 or so.  Also the connection drops and restarts periodically.  Window 8.1 on the same machine works like a charm and I have no such problems in Ubuntu 14.10.  What could be the issue?  I'm happy to provide diagnostic information on request.  Normal performance after reboot    After some time using the Internet    Diagnostics  $ lspci -knn | grep Eth -A2 00:19.0 Ethernet controller [0200]: Intel Corporation 82579V Gigabit Network Connection [8086:1503] (rev 05)     Subsystem: ASUSTeK Computer Inc. P8P67 Deluxe Motherboard [1043:849c]     Kernel driver in use: e1000e -- 07:02.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet [10ec:8167] (rev 10)     Subsystem: ASUSTeK Computer Inc. Device [1043:820d]     Kernel driver in use: r8169
I have installed Ubuntu Server on an old desktop, and I'm new to this.  I had set it up and was trying to connect through Putty but that was not working.  When I tried ifconfig there was no eth0 IP address, and logging onto the router showed the only device connected by ethernet is the printer.  However, the ethernet cable is plugged into the server and is showing the green light by it.  I tried opening /etc/networking/interfaces but this shows the following:  source /etc/network/interfaces.d/*  # The loopback network interface auto lo iface lo inet loopback   I tried adding 'auto eth0' after this and saving but made no difference, and have tried sudo ifconfig eth0 up which didn't do anything either.  sudo lshw -C network says that the network is DISABLED.  Any ideas to help get this up and running?  EDIT: Running command lspci -knn | grep Eth -A3 results in the following:  02:05.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet [10ec:8167] (rev 10)          Subsytem: Gigabyte Technology Co., Ltd GA-MA69G-S3H Motherboard [1458:e000]          Kernel driver in use: r8169          Kernel modules: r8169
Today I downloaded Ubuntu for my laptop. It runs great from a bootable USB, but when I tried to install it, I got the following error message: The installer encountered an error copying files to the hard disk:  [Errno 5] Input/output error  This is often due to a faulty CD/DVD disk or drive, or a faulty hard    disk. It may help to clean the CD/DVD, to burn the CD/DVD at a lower   speed, to clean the CD/DVD drive lens (cleaning kits are often    available from electronics suppliers), to check whether the hard disk   is old and in need of replacement, or to move the system to a cooler   environment.     I tried everything to install it on my laptop including redownloading the Ubuntu ISO image, but nothing worked. Assume I have a flight ticket from A->B->C and at A I checked in luggage all the way to C. However after the first flight I don't board the second flight but decide to remain in B.  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Used to be that I could be logged into one set of sites with the first user and a different set with the other users.    But now I am logged in with the Account-A on Site-1.  When I go to one of the sites I use the other account for and click "log in" under the SE menu, I go to a page where I only have an option to confirm creation of an account based on my Google login.  It does not present a way to log in with an SE account.    How can I log in with my other account here?  (and before you flag this as a duplicate, please ensure the other question is recent enough and that the answer is relevant.  This behavior has definitely morphed over the years... and I am having trouble finding something that is relevant.  For instance this question  simply points out how to merge the accounts which is NOT what I want  .  This question  talks about presenting different user info on each site but that's not what I want -- I want totally separate accounts). 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