Question Suddenly can't access my home network PCs remotely

[Shmendrapolk]

I usually connect remotely to my home network through a an assigned URL using one of these free services and it is suddenly not working.
It's not the service as I've been testing with the actual IP address.

When I try to connect via VNC or using qbittorrent's web interface I get a "ERR_CONNECTION_REFUSED" (qbittorrent), VNC tells me target machine actively refused the connection. VNC will work only if I use my internal IP address, which
I've been testing within network and from without (though limited this way by using my phone and turning wifi off). Same issue using my Subsonic music streaming.
I went to a website to check if my forwarded ports are open and all the ones that are forwarded are allegedly closed.
I tried forwarding a new port just as a test,
I've tested remote accessing of multiple PCs on the network, so it isn't an issue with one particular machine.
My router is otherwise working fine. I've rebooted it and that hasn't helped.
I have a Netgear R6700
I connected my old Netgear router as a test, same problem.
My internet connection is working fine.
I can ping my external IP address without issue.

I called my ISP. They did some diagnostics, including a reset of my modem, but no change. They said it isn't their problem because my internet connection works, that's the only service they provide, they don't block traffic.

So it's not my router, it's not one particular PC, and it's not one particular app, since it's an issue across the board.

Any ideas? My IPS told me I can bring my modem in and exchange it but I honestly don't see how that would matter.

I really need to fix this.

 

[mxnerd]

Try another DDNS service. Or use Teamviewer.

 

[Shmendrapolk]

But if I enter the IP address directly , why would the DDNS Service be a factor.

Moreover, that should have no impact on using subsonic, which assigns domain names with their licences: xxxx.subsonic.org

Also why would the portchecker website tell me my ports are closed.

 

[SamirD]

So all things being the same, something isn't. Something definitely changed somewhere that is causing this issue.

My hunch is that if you haven't updated anything manually, it was some sort of automatic update that broke it.

 

[Shmendrapolk]

OK I was messing around in the Router settings: I set my PC with my music server and torrent client to be a DMZ server. Sure enough I can access the machine from the outside. Ports that are routed to that machine are open according to port checker.
Now obviously this isn't a solution, as (1) presumably keeping my PC in DMZ zone isn't safe (2) doesn't solve the problem of other computers on the home network.

But this does mean it is a router issue, no? If anyone could walk me through the router settings that would fix this, that would be great.

 

[SamirD]

Nice diagnostic work.

Okay, so if it's in the router, the first thing to determine is how it got that way. Did you do anything to change the firmware or make any type of changes to the router? When was the last time the router was rebooted?

 

[Shmendrapolk]

Nice diagnostic work.

Okay, so if it's in the router, the first thing to determine is how it got that way. Did you do anything to change the firmware or make any type of changes to the router? When was the last time the router was rebooted?

I updated the firmware today *AFTER* this began just as a precaution to ensure the firmware wasn't fixing some sort of issue related to this.
I rebooted the router earlier today because the internet went down. I do reboot periodically (pulling the plug out) as the 2.4gh network has a habit of flaking out on me.
But I haven't changed any settings. And I haven't done a reset of any sort, certainly not since last night, when this was working perfectly fine.
The fact that my old router, which was sitting in a box for 2 years has the same problem (though also a Netgear, same GUI more or less) makes this perplexing.

 

[SamirD]

Hmmm...two routers usually can't do this since they both can't have something going on at the same time.

What does your router plug into Internet-wise? Also, what are the model numbers of your current router and the netgear one?

 

[Shmendrapolk]

Current router is a Netgear AC1750.

It plugs into the modem. And there's tons of devices connected to the router, some hard wired, some wifi.
All the ones with forwarded ports are ethernet, some plugged into the router directly, others plugged into an an ethernet switch.

If the "target machine" is actively refusing the connection, isn't this getting logged somewhere? I mean there must be some way of knowing if the machine doing the rejecting is the router, a PC, etc?
Again I don't think it can be a PC for the reasons I outlined above and if I pick a random port that's not forwarded I get the same error, which presumably means it's getting stopped by the router since it isn't actually being directed to a particular computer.

Am I correct in thinking that the DMZ pass through rule out the modem as a cause?

 

[SamirD]

Thank you. So it's just a straight modem, right? No combos or anything like that?

Logging is not the greatest on anything Netgear that I own, and I've got a lot of their gear. I think the router is simply not opening the ports for whatever reason, as you've proven by it blocking non-open ports in the same manner.

The dmz definitely helped rule out the system as a cause, and a modem wouldn't be blocking ports unless it was acting like more than a modem.

From what you mentioned earlier about your setup, it sounds like you have more than one computer and more than one that has port forwarding going to it, correct? I'm assuming then you must be using dhcp reservations on your systems correct?

What I'd like for you to try is to try assigning a different IP address to the system you want port forwarding to work on, and then change the rules to reflect the new IP and let's see what happens.

The other experiment I would want to try is to disconnect one of the other systems where port forwarding is working and put this system there and change any rules as needed to have the forwarding work for the applications you want.

My hunch is that something is broken/corrupted in the firmware or data area of the firmware that's causing this issue. If port forwarding works in either of the above scenarios, then we have a workaround as I don't know how the router could be fixed if the firmware flash memory has gone bad.

 

[mxnerd]

Check Windows Firewall. Check Network Profile (Private or Public)

Also run CurrPorts to see what ports are open.

CurrPorts: Monitoring TCP/IP network connections on Windows

CurrPorts displays the list of all currently opened TCP/IP and UDP ports on your local computer.

www.nirsoft.net

 

[Shmendrapolk]

I fixed it! Sort of.

I deleted one of the forwarded ports, then set it up again, and sure enough it works now. Tried it with a couple more. I'll have to do it for all of them.
I honestly don't understand why this is, but at least I solved it. I hope it isn't a bug that comes back.

By the way the page I go to to check if a port is open automatically inserts by IP address and port 80. Is port 80 supposed to be open, or is it just listed there as an example?

 

[SamirD]

Check Windows Firewall. Check Network Profile (Private or Public)

Also run CurrPorts to see what ports are open.

CurrPorts: Monitoring TCP/IP network connections on Windows

CurrPorts displays the list of all currently opened TCP/IP and UDP ports on your local computer.

www.nirsoft.net

The system doesn't have any issues since it works in the dmz.

 

[SamirD]

I fixed it! Sort of.

I deleted one of the forwarded ports, then set it up again, and sure enough it works now. Tried it with a couple more. I'll have to do it for all of them.
I honestly don't understand why this is, but at least I solved it. I hope it isn't a bug that comes back.

By the way the page I go to to check if a port is open automatically inserts by IP address and port 80. Is port 80 supposed to be open, or is it just listed there as an example?

I was suspecting it was something like this. Glad to hear you were able to fix it. I've had to do this on one of my routers as well, but for IPsec vpn tunnel configurations--can only be some sort of storage corruption.

I would keep an eye on it if it does come back. I'm not sure if you're under warranty, but this would be a warranty issue if you try upgrading and downgrading the firmware to other versions and the issue persists.

I think it inserts port 80 because that's common when someone allows remote management or sets up a web server. It would be interesting to know which is the most common port used on residential routers, but I would suspect it is probably port 80.