Zkusil jsem tedy nastavit "Umožnit ostatním uživatelům v síti využívat připojení k internetu tohoto počítače", ale nefunguje to.
Kdyby někdo zkušený vyčetl, kde je chyba, tak zde je:
>>>> Konfigurace nového PC (=zdrojového, s Windows 7):
[System tray]
Network: Internet access
Unidentified network: No Internet access
┌──────────────────┐
│ Internet UPC cable USB
│ Network, Shared
│ Motorola SURFboard....
└──────────────────┘
┌──────────────────┐
│ PC-to-PC & ICS
│ Unidentified network
│ Intel(R) 82566DM-2...
└──────────────────┘

[PC-to-PC & ICS]
Unidentified network
Intel(R) 82566DM-2 Gigabit Network Connection
--------------------------------------------------
Conn.-spec.DNS Suffix :
Physical Address. . . : 00-22-64-B4-9A-28
DHCP . . . . . . . . . . : Enabled
Autoconfiguration . . : Enabled
[IPv4]
Address . . . . . . . . : 192.168.0.1(Preferred)
Subnet Mask . . . . . : 255.255.255.0
Default Gateway . . . :
DNS Server. . . . . . :
WINS Server . . . . . :
NetBIOS over Tcpip. . : Enabled
[IPv6]
Link-local Address . . : fe80::1cce:9bb9:44e0:48d5%10(Preferred)
Default Gateway . . . :
DHCP IAID . . . . . . . : 234889828
DHCP Client DUID . . : 00-01-00-01-1A-FF-2E-B6-00-22-64-B4-9A-28
DNS Servers . . . . . . : fec0:0:0:ffff::1%1
. . . . . . . . . . . . . . . : fec0:0:0:ffff::2%1
. . . . . . . . . . . . . . . : fec0:0:0:ffff::3%1

[Internet UPC cable USB]
Network, Shared
Motorola SURFboard SB5100 USB Cable Modem
--------------------------------------------------
Conn.-spec.DNS Suffix :
Physical Address. . . : 00-0C-E5-82-A4-B5
DHCP . . . . . . . . . . : Enabled
Autoconfiguration . . : Enabled
[IPv4]
Address . . . . . . . . : 89.102.91.41(Preferred)
Subnet Mask . . . . . : 255.255.255.0
Default Gateway . . . : 89.102.91.1
DHCP Server . . . . . : 10.131.176.1
DNS Servers . . . . . : 213.46.172.37, 213.46.172.46
WINS Server . . . . . :
NetBIOS over Tcpip. . : Enabled
[IPv6]
Link-local Address. . : fe80::a57c:29ae:1dc1:481d%11(Preferred)
Default Gateway . . . :
DHCP IAID . . . . . . : 335547621
DHCP Client DUID. . : 00-01-00-01-1A-FF-2E-B6-00-22-64-B4-9A-28
DNS Server. . . . . . :

Tunnel adapter 6TO4 Adapter:
--------------------------------
Conn.-spec.DNS Suffix :
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration . . . . . . . : Enabled
IPv6 Address. . . . . . . . . . . : 2002:5966:5b29::5966:5b29(Preferred)
Default Gateway . . . . . . . . . : 2002:c058:6301::1
DNS Servers . . . . . . . . . . . . : 213.46.172.37, 213.46.172.46
NetBIOS over Tcpip. . . . . . . . : Disabled