Windows 10 Limited Connectivity fix

Recently, my sister had problem with laptop runing windows 10. It lost the internet contectivity after recent "Wana cry fixes". Surely the fix was not directly connected with the issue (it has to be some other patch or coincidence).

TLDR; To fix the issue try following commands:

netsh winsock reset catalog (Reset WINSOCK entries to installation defaults)
netsh int ipv4 reset reset.log (Reset IPv4 TCP/IP stack to installation defaults)
I had only limited knowledge what really was the cause since I didn't had access to the computer. The only way to interact was giving instruction to my sister to type proper commands ;)

So first let's try to ping the gateway.

C:\Users\Leszek>ping 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.50: Destination host unreachable.
Reply from 192.168.1.50: Destination host unreachable.
Reply from 192.168.1.50: Destination host unreachable.
Reply from 192.168.1.50: Destination host unreachable.

Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Suspecting that host does not have IPv4 assigned by DHCP, lets check:

C:\Users\Leszek>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : DESKTOP-UOL3AHR
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : home

[SNIP] ...

Wireless LAN adapter Wi-Fi 2:


Connection-specific DNS Suffix . : home
Description . . . . . . . . . . . : Atheros AR9271 Wireless Network Adapter
Physical Address. . . . . . . . . : 74-EA-3A-90-27-44
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2a01:11af:2d9:cb00:b9a0:fb37:6b91:4be4(Preferred)
Temporary IPv6 Address. . . . . . : 2a01:11af:2d9:cb00:b49e:1d17:8dc1:b53d(Preferred)
Link-local IPv6 Address . . . . . : fe80::b9a0:fb37:6b91:4be4%7(Preferred)
Autoconfiguration IPv4 Address. . : 169.254.75.228(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : fe80::8616:f9ff:fef9:2ef6%7
DHCPv6 IAID . . . . . . . . . . . : 477424186
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1E-18-3A-61-00-1D-09-40-2D-77
DNS Servers . . . . . . . . . . . : 2a01:11af:2d9:cb00:8616:f9ff:fef9:2ef6
NetBIOS over Tcpip. . . . . . . . : Enabled
Connection-specific DNS Suffix Search List :
home[SNIP] ...

Yup, seems that autoconfiguration kicks in:
Autoconfiguration IPv4 Address. . : 169.254.75.228(Preferred)

But ... if so ... than what is this 192.168.1.50 which reply for ping. Usually this is local ip, but ... local IP is different. So ... it seems to be remote IP and the routing table is broken?
Lets try to examine both tables:

C:\Users\Leszek>route print
===========================================================================
Interface List
29...72 ea 3a 90 27 44 ......Microsoft Hosted Network Virtual Adapter
19...00 1d 09 40 2d 77 ......Marvell Yukon 88E8040 PCI-E Fast Ethernet Controller
15...00 ff ac 02 bb f6 ......Kaspersky Security Data Escort Adapter
7...74 ea 3a 90 27 44 ......Atheros AR9271 Wireless Network Adapter
1...........................Software Loopback Interface 1
8...00 00 00 00 00 00 00 e0 Microsoft Teredo Tunneling Adapter
18...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
===========================================================================

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
127.0.0.0 255.0.0.0 On-link 127.0.0.1 331
127.0.0.1 255.255.255.255 On-link 127.0.0.1 331
127.255.255.255 255.255.255.255 On-link 127.0.0.1 331
169.254.0.0 255.255.0.0 On-link 169.254.75.228 306
169.254.75.228 255.255.255.255 On-link 169.254.75.228 306
169.254.255.255 255.255.255.255 On-link 169.254.75.228 306
224.0.0.0 240.0.0.0 On-link 127.0.0.1 331
224.0.0.0 240.0.0.0 On-link 169.254.75.228 306
255.255.255.255 255.255.255.255 On-link 127.0.0.1 331
255.255.255.255 255.255.255.255 On-link 169.254.75.228 306
===========================================================================
Persistent Routes:
Network Address Netmask Gateway Address Metric
0.0.0.0 0.0.0.0 192.168.1.1 Default
===========================================================================

IPv6 Route Table
===========================================================================
Active Routes:
If Metric Network Destination Gateway

C:\Users\Leszek>arp -a -v

Interface: 127.0.0.1 --- 0x1
Internet Address Physical Address Type
224.0.0.22 static
224.0.0.252 static
239.255.255.250 static

Interface: 169.254.75.228 --- 0x7
Internet Address Physical Address Type
169.254.255.255 ff-ff-ff-ff-ff-ff static
224.0.0.22 01-00-5e-00-00-16 static
224.0.0.251 01-00-5e-00-00-fb static
224.0.0.252 01-00-5e-00-00-fc static
239.255.255.250 01-00-5e-7f-ff-fa static

Interface: 0.0.0.0 --- 0xffffffff
Internet Address Physical Address Type
224.0.0.22 01-00-5e-00-00-16 static
224.0.0.252 01-00-5e-00-00-fc static
239.255.255.250 01-00-5e-7f-ff-fa static

Interface: 0.0.0.0 --- 0xffffffff
Internet Address Physical Address Type
169.254.75.228 00-00-00-00-00-00 invalid
169.254.153.184 00-00-00-00-00-00 invalid
192.168.1.1 84-16-f9-f9-2e-f6 invalid
192.168.1.2 00-00-00-00-00-00 invalid
192.168.1.4 00-00-00-00-00-00 invalid
192.168.1.15 00-00-00-00-00-00 invalid
192.168.1.255 ff-ff-ff-ff-ff-ff static
224.0.0.22 01-00-5e-00-00-16 static
224.0.0.251 01-00-5e-00-00-fb static
224.0.0.252 01-00-5e-00-00-fc static
224.0.0.253 01-00-5e-00-00-fd static
239.255.255.250 01-00-5e-7f-ff-fa static

Interface: 0.0.0.0 --- 0xffffffff
Internet Address Physical Address Type
224.0.0.22 01-00-5e-00-00-16 static
224.0.0.252 01-00-5e-00-00-fc static
239.255.255.250 01-00-5e-7f-ff-fa static

There is no 192.168.1.50 either in ARP not routing table ... so what is this IP? Is this local IP somewhere in crappy windows IP stack or some cached IP? What is going on?

How the heck Windows administrator are debugging such things?

My Windows are limited (god bless) and I didn't want to force my sister to run Wireshark to solve the mystery about this 192.168.1.50. For sure no such host exist in the network, and TTL suggest that it is some magic IP used by local windows stack.

Fortunately my brother found following "magic" commands xD, which reset the windows IP stack. xD
You get it ... no clue what is going on, so let's reset all the magic inside windows stack to default xD

C:\WINDOWS\system32>netsh winsock reset catalog

Sucessfully reset the Winsock Catalog.
You must restart the computer in order to complete the reset.

C:\WINDOWS\system32>netsh int ipv4 reset reset.log
Resetting Global, OK!
Resetting Interface, OK!
Resetting Unicast Address, OK!
Resetting Neighbor, OK!
Resetting Path, OK!
Resetting Route, OK!
Resetting , failed.
Odmowa dostępu.

Resetting , OK!
Restart the computer to complete this action.


And it works after reset ...
God ... I HATE Windows!

Edit:
After applying fix we ping this strange host, to confirm it wasn't present on network:

C:\Users\Leszek>Ping 192.168.1.50
Pinging 192.168.1.50 with 32 bytes of data:
Reply from 192.168.1.5: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Ping statistics for 192.168.1.50:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

How Windows admins are able to debug things on this crappy operating system is still mystery for me.

Update: some other sources adds following commands:

netsh int reset restlog.txt
netsh int TCP set heuristics disabled
netsh int TCP set global autotuninglevel=disabled
netsh int tcp set global RSS=enabled