I bought the Plus Switch-GS105E V2 so I could "see" both PC's, but ...

WOW   - lotta HOMEWORK ( l8r - I work SOOOO Slow)

Thanx for valuable cklist  & prompt reply 

J

.. Answers from Joe as of 10/21/21
re: 1a Are all your computers on the LAN (?)
I M unsure -[ What is a simple way / command to provide that Info?]

re: ..1b { Are all your computers on the LAN, and .. }
..1b the link LED show links and activity (on the switch ports and the computers)? ..
Unsure ("link LED"?)

..1c
.. able to reach the Internet?
Yes

..1d
.. behind a router,
? I Don't Know how to answer that question. .... but ...
My Equipment: includes NetgearC6900 – High Speed Cable Modem Router

.. and have IP addresses (typially assigned by the router DHCP) in the RFC1918 IP range, like for example 192.168.0.x or 192.168.0.x?
Yes - 192.168.0.1

2
.. Windows 10/11 systems configured to be on a Private Network Location? ..
(yes ?) I think they are now. *
(I had wanted to do "Private", since I am able to provide passwords {into all the keyboards in the house}, & ..
since I assumed that "public" meant vulnerable to intruders.)

* {I have run every Trouble Shooter I could find, but the information is usually insufficient for reaching a solution.}

PS:
Network
( partial Report from Speccy, October 21, 2021)
You are connected to the internet
Connected through Intel Ethernet Connection I217-V
IP Address 192.168.0.46 Subnet mask .... DHCP Enabled
DHCP server ... External IP Address ...
Adapter Type Ethernet
NetBIOS over TCP/IP Enabled via DHCP
NETBIOS Node Type Hybrid node Link Speed 0 Bps
Computer Name
NetBIOS Name DESKTOP-____VAT ..DNS Name
Membership Part of workgroup
Workgroup WORKGROUP
Remote Desktop Enabled
Console State Active
Domain DESKTOP-____VAT
RDP-Tcp State Listen
-WinInet Info LAN Connection
Local system uses a local area network to connect to the Internet
Local system has RAS to connect to the Internet
Wi-Fi Info Wi-Fi not enabled (B/c Netgear C6900 Modem / Router IS enabled)
WinHTTPInfo
WinHTTPSessionProxyType No proxy
Session Proxy
Session Proxy Bypass
Connect Retries 5
Connect Timeout (ms) 60,000
HTTP Version HTTP 1.1
Max Connects Per 1.0 Servers INFINITE
Max Connects Per Servers INFINITE
Max HTTP automatic redirects 10
Max HTTP status continue 10
Send Timeout (ms) 30,000
IEProxy Auto Detect Yes
IEProxy Auto Config
IEProxy
IEProxy Bypass
Default Proxy Config Access Type No proxy
Default Config Proxy
Default Config Proxy Bypass
Sharing and Discovery
Network Discovery Enabled
File and Printer Sharing Enabled
File and printer sharing service Enabled
Simple File Sharing Enabled
Administrative Shares Disabled
Network access: Sharing and security model for local accounts Classic - local users authenticate as themselves
Adapters List
Enabled
Bluetooth Device (Personal Area Network)
Connection Name Bluetooth Network Connection
DHCP enabled Yes
MAC Address .....
Intel(R) Ethernet Connection I217-V
Connection Name Ethernet
NetBIOS over TCPIP Yes
DHCP enabled Yes, MAC Address ....
IP Address ... Subnet mask ...
Gateway server... DNS Server ... / DHCP 192.168.0.1
. etc
Network Shares Users C:\Users
Current TCP Connections...
. etc

PPS:
I am expecting another switch today (NETGEAR Switch GS305) {5-Port Gigabit Ethernet Unmanaged}.

Thanx,
J