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I have a Windows 11 PC sharing its (wireless LAN) Internet connection via an Ethernet adapter (192.168.137.1/24):

Wireless LAN adapter WLAN:

   Connection-specific DNS Suffix  . : router.local
   IPv4 Address. . . . . . . . . . . : 192.168.178.62
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.178.1

Ethernet adapter Ethernet 6:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::c473:b359:2bd3:fb0%3
   IPv4 Address. . . . . . . . . . . : 192.168.137.1
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :

enter image description here

A second PC (connected via Ethernet) has the following setup for its Ethernet adapter:

Ethernet-Adapter Ethernet 2:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::51e6:fd36:9678:15fb%12
   IPv4-Adress . . . . . . . . . . . : 192.168.137.2
   Link-local IPv6 Address . . . . . : 255.255.255.0
   Standardgateway . . . . . . . . . : 192.168.137.1

the routing table has the correct entry:

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0    192.168.137.1    192.168.137.2    281
(...)

===========================================================================
Persistent Routes:
  Netzworkaddress          Netmask    Gatewayaddress  Metric
          0.0.0.0          0.0.0.0    192.168.137.1  Standard
===========================================================================

the PC's can ping each other (on 192.168.137.1 and 192.168.137.2) but pinging 8.8.8.8 from PC2 does not work anymore (as far as I remember it used to work after I first tried the setup). Any idea what the problem might be?

I tried:

  • the Internet connection is working for PC1
  • deactivating the firewall on PC1 didn't improve anything
  • deactivating IP6 (both adapters) didn't improve anything
  • tracert just shows timeouts
Albin
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  • Consider packet capture on PC1? – Tom Yan May 12 '22 at 13:23
  • @TomYan not yet, I didn't set up Wireshark yet (I hope there is a simpler solution) – Albin May 12 '22 at 13:26
  • Try disable and re-enable the ICS, heh (smells like something wrong with the NAT, so if possible, perhaps it's even better to packet capture on PC1's default gateway). – Tom Yan May 12 '22 at 13:40
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    reinitializing the ICS did the trick... should have tried that in the first place, thanks! – Albin May 12 '22 at 14:24
  • @TomYan Restarting the laptop would have probably done the trick as well, feel free to write an answer. – Albin May 14 '22 at 08:10
  • Out of curiosity, what was your approach to troubleshot via packet capture? – Albin May 14 '22 at 08:13
  • To be frank, I don't have a better solution attempt than resetting / toggling ICS anyway. (Isn't resetting / toggling the way to fix things in Windows for most of the time though?) I was just kinda curious whether it was due the IP forwarding is down, or whether the NAT'ing is down / has gone haywire somehow. – Tom Yan May 14 '22 at 08:22
  • @TomYan Seems to be a common issue, it happened a few times now, and reinitializing always helped. If you want to add an answer, feel free, otherwise, I can do it as well in order to resolve the question. – Albin May 16 '22 at 10:43

1 Answers1

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Resetting the internet sharing worked fine. Although I ended up creating a WLAN to Ethernet bridge which ended up being much more stable.

Albin
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