If Proxy settings will not stay unchecked, pc is most likely infected by a virus. First thing to run before performing the following solutions is to run some kind of malware remover ie. malwarebytes, hitman pro, rkill etc.
Proxy settings
By default it will keep proxy lan settings enabled like this:
Proxy server enabled, if you untick and click okay the settings will
not change. this is not relient on restarting the computer or anything
else that you would assume it simply will not turn it off.
If LAN Settings is Greyed out Open "Regedit" navigate to HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings and set ProxySettingsPerUser = 1
If you want to disable the proxy server its usually as simple as
unticking the "use proxy server" box. in windows 8.1 this is not the
case, upon closing that dialogue box it will sometimes reset back to
being enabled again. The only way i have found around
this is as follows.
Tick the "Use automatic configuration script"
Type in "http://localhost/proxy.pac" without the quotation's
Untick "Use a proxy server for your LAN"
The proxy.pac address must use // and not \\ as for some reason if you
use the lan address it automatically changes it back to using the lan
proxy. dont worry if you do not have a proxy.pac file if you have
"automatically detect settings" selected it should
default to no proxy. but stupidly enough this is the only way to
disable a proxy server in windows 8.1
(this has happend a few times randomly with windows 7 enterprise and
resetting internet explorer to defaults fixes this, in windows 8.1
however that does not help at all)
Test again, see if your internet is working.
Problem persists
You can also manually set it through registry editing.
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\
"MigrateProxy"=dword:00000001
1 for enable 0 for disable
"ProxyEnable"=dword:00000000
1 for enable 0 for disable
"ProxyHttp1.1"=dword:00000001
1 for enable 0 for disable Might also be "ProxyHttp1_1" on some machines
"ProxyServer"="" This is blank (if there's a value Delete it)
if you are actually using a proxy server, the format is IPaddress:port
If the registry Keys above aren't shown Add them.
Right click New>DWORD(32-bit Value)
give it its name, right click and Modify... type in its value from above.
Still not working
if that still doesn't work there is most likely a virus that is effecting the following registry key
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections\DefaultConnectionSettings
The only important part of this binary is the first octet of the 0008 line underlined/highlighted below.
0000 00 00 00 00 00 00 00 00
0008 03 00 00 00 00 00 00 00
bit of info on what that octet does;
09 makes it "automatically detect settings" disable proxy and all other LAN settings
03 is most likely what it is set to currently and that is for when proxy is enabled only
0B is when both are enabled but proxy will still take over
05 is when "use auto config script" is enabled
0D is when auto detect and auto config are enabled
07 is when auto config and lan are enabled
0F when everything is enabled
01 when nothing is enabled
Change it to this (only the highlighted part is important leave the rest default)
to make the change when right clicking and editing place your cursor infront of the 09 in the example above backspace
once it will delete 03 then type 09 click okay and now your internet will work.
Another known program that causes this issue is "Rocket Tab" you can
uninstall it from your add and remove programs list, I've seen it many
times on various computers that it installs itself and changes your
proxy address preventing you from using the internet
at all, after uninstalling you can set your proxy back and it should
just work.