Can a hacker access a subnet computer, when they are not on the subnet?

[booradlly]

Is there anyway a hacker can gain access to a computer on a subnet, he/she has not been given access to?

I really like physical security over, digital security. Because of this, in my house, I didn’t really want wifi at all. With all physical connections, a hacker would have to get into my house or come through my ISPs router.

Since everything on my side of the ISP router is on a different subnet than the actual internet. A hacker could not access any of my computers directly correct ?

If I add a router to my side of the ISP router and enable wireless on the ISP router, and put all my computers on the new router. My computers will be able to see and access computers off the ISP router. But computers off the ISP router, will not be able to see or access my computers correct?

All of this is assuming I don’t add specific routes to the routers to gain access to the subnet comps.

Basically if someone is able to hack my wifi, or even hack my ISP router, I want them to then have to hack my router before they can get to me.

Before anyone suggests guest wireless, every implementation I have seen requires you to enable the normal wireless also. So if someone knows of an implementation that doesn’t, I’m all ears.

Routers at my disposal: AC1900, WRT600N, Almond+

Caveat: My computers require IPv6, WRT600N does not support, AC1900 does, don’t know about Almond+

Background: Took a 7-day boot camp on CCNA, currently studying for it (so I know very little). First post in forums, feel free to tell me I’m doing it wrong.

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

In that subnet has network connectivity to/from the hacker's subnet, in theory, yes you can be hacked.  In practice, you can impose barriers between subnets to make to very, very difficult for the hacker to cross between subnets.  Also, how your host devices are configured also creates barriers.