Cable TV ISP Broadband Security Issue

Recently I have switched to a local Cable TV Internet Service. These guys do not provide any modem inside the house. Their modem is located outside from where various branched-out wired lan connections are provided to customers.Thus I have a direct lan cable into my computer's lan port. Now the problem is when I go to My Computer -> Networks, I can see a bunch of unknown computers ( who are of course the other consumers and may be an admin).
https://drive.google...iew?usp=sharing
I was worried if any of those computers could actually access my files. So I tried to access theirs from my side. I was surprised to see that any computer without a windows password could easily be accessed. For example \\jack-Pc\C:, was showing shared drives on that PC . Those with windows password could not be accessed though.
Just to make things clear, this has nothing to do with internet connection. Whether the internet is on or off, just the lan cable plugged in shows all these computers.
If I turn off network discovery all the computers vanish, google tells me that network admins can access files inspite of network discover/file sharing settings. If I run 'net share' in command prompt it shows all my drives have admin share. So I am afraid that the admin of this stupid network (who could be the isp guys) can actually access my files.Well I googled how to turn admin share off tryu regedit and applied that, but I have the following questions in mind.

1) Can a network admin access my files and folders without knowing my windows login credentials?
2) If i disable admin share thru regedit, can he still access my files?
3) I have noticed putting a router in between the lan cable and my computer, makes these computers vanish. So can my personal router serve as a security shield in this case?

Just to add, unlike in corporate scenarios where network admin has all rights and the user doesn't have admin rights, here I have complete admin rights on my machine. I am just afraid if the n/w admin of this network also shares the same privilege.

another point: My antivirus is warning me of duplicate ips, when I am connected to this network.
https://drive.google...iew?usp=sharing

ps: These guys are no tech guru, so I am not afraid of someone brute forcing my password. Just want to prevent easy regular access t my private files due to my ignorance.

I am pretty much sure you can use a router in between that LAN and your computer. Perhaps something with wireless and 4-ports as well if you have a phone/tablet/laptop another PC etc.

This way the routers outer port will get IP from cable company with Internet IP. And your computer will get a local IP, hence separating the networks. And should be able to keep the average Joe out of your network.

Until you get a router, make sure your internet connection is configured as public.

What kind of internet connection did you have before, maybe your old device is compatible and up to the task? If not make sure the router you get is compatible (usually cable routers are different than adsl routers etc - different authentication methods). Ask around or perhaps a local forum for your ISP.

Examle: Linksys Wireless Routers - WRT, Wireless-AC and Smart Wi-Fi there are many brands for routers, not necessarily Linksys.

Regarding your concern: No that admin doesn't have any credentials on your local machine and can't access. But it is not a good practice to expose yourself like that. Not having a password ofcourse is a security issue.

Hope this is clear.

Well previously i had an ADSL connection so that modem won't work. But I have already installed a WAN port + 4 lan router. A few friends suggested changing the default IP of the router so I did that too.
Well you statement "Regarding your concern: No that admin doesn't have any credentials on your local machine and can't access. " is a big relief. Because as it happens in my office, the network admin is like GOD and kind of has a master password or something, and can enter our windows machines whenever he wishes to. I hope you are confirming this is not the case here.
A few people were suggesting VPN and stuff, but I would really love to hear that the router would solve the problem.
Also do you suggest changing any permission in the security tab of the hard drives?

Yes, the administrator of a domain is indeed very powerful and can do whatever he likes. An enterprise admin being the most powerful one (back when I worked the best practice was to divide that password into 3 parts, only 1 person knowing a part and keep them separate in fireproof safes etc ).

But you are not in the ISP domain and have nothing to fear in that regard.

You can still configure your network as public if you are the only computer so it will add some more security. (Open Network and Sharing Center, under Network change to public)

Thanks GoKay, I have set the network to public.
Just to bother you a bit more, can I be sure that i am not in the ISP domain? Doesn't unknown computers showing up in my network indicate that I might be part of the domain? Pardon me if I am misunderstanding what you refer to as domain. enlighten me please.

Nah, they will show when you are in the same network, usually first 9 numbers of your IP number (depends on subnet mask really, when subnet mask is 255.255.255.0=first 9 letters).

Search "image windows 7 domain login screen" in google and see the pictures. The login screen change a bit when in domain (you get an option to login with domain or local computer credentials)

The image search was very helpful. I guess when you right click on My Computer - > properties - > computer name domain and workgroup settings - > change computer name_> it shows I am a member of workgroup and not any domain. In order to be a part of the domain we have to put a domain name in that window.

I will tell you what my stupid brain has inferred. ( i would dump my computer and sell bananas from tomorrow I promise )
My cable ISP gave me the following values ( ip address, subnet mask, default gateway, primary and secondary DNS) . Now all my neighbors who are consumers of the ISP must have got the same first 9 digits of the subnet mask(255.255.255), and thus can see each other in our network. Now when I fed these values into my router and connected to the internet, the router separates the isp network and my own network, and thus I get rid of my neighbors.
AM i right? By the way my router's subnet mask also begins with 255.255.255, but that doesn't make me part of that isp network somehow?!

Subnet mask on its own doesn't mean anything. Maybe there is info about how it works in these forums, you have to search :)