RT-AC3100 Issue with Visual Studio Connection

[DMoody007]

I am a programmer that uses Visual Studio for development work. I hooked up an Asus RT-AC3100 router the other day and it is working for almost everything except the one main thing I need. My ability to connect to a remote website with Visual Studio via FTP.

I can connect to the website without issue. It will connect and show me the folders and files on the site. I can navigate the files like using File Explorer. The issue is that I can not open the pages in the software to edit or save. I get an error that I can not access the file.

If I bypass the router by directly connecting to the internet or connecting through a cell phone hotspot, I have no issues with the Visual Studio working as expected. The moment I try to go through the Asus router, it fails.

I am used to programming some firewalls and routers but this one stumps me.

• I have disabled the firewall and it doesn't make a difference
• I queried Visual Studio for ports needed and I have ensured the ports are open in port forwarding but no luck
• What I find disturbing is logging. There doesn't appear to be any logging that shows detailed traffic, what is being allowed and what is being blocked.
• I am also missing being able to see specific firewall rules to try and debug what is being allowed and disallowed

Hoping someone with more experience than I with Asus Routers can give me a direction for how to debug this router. How to determine what is being blocked and how to unblock its traffic but still keep the router somewhat secure.

 

[Tech9]

If I bypass the router by directly connecting to the internet

What is the ISP device?

- Modem (your Asus is getting public WAN IP)
- Gateway (your Asus is getting private WAN IP)

If you need port forwarding and your Asus is behind ISP Gateway - you have another firewall upstream.

 

[DMoody007]

Hello - Thanks for responding.
I have Spectrum. I had a Spectrum Cable Modem and a Spectrum Wifi Router. The router died and I decided to use this Asus router in its place instead of paying Spectrum rent on their router. It was new in box and just collecting dust. The modem is still the same. If I connect the PC directly to the modem, I have no issues so I don't think the modem applies in this case.

 

[Tech9]

You have to provide more specific information about the FTP error and the devices involved. FTP has Passive and Active mode. It changes the way the connection is established. Spectrum Cable Modem doesn't say much. What firmware is your Asus router running (latest available stock Asuswrt?), are you getting public WAN IP from ISP DHCP (confirm), is UPnP enabled (default), what do you see in port forwarding status (System Log menu, Port Forwarding tab), etc. information may also help.

 

[bennor]

The RT-AC3100 is End of Life. Is there any particular reason why you (I assume) replaced your previous Internet router with the end of life Asus router? That Asus router is apparently on the old 3.0.0.4.386_x firmware track.

I get an error that I can not access the file.

For context, what is the specific error message you are receiving?
What router was the Asus router replacing?

As already asked, post what firmware the router is running and how is it configured.
If running Asus-Merlin firmware do you have any addon scripts installed or active?
What changes from their default settings have you made to the Asus router when you installed it?
What is the Asus router WAN port connected to upstream?

As a last troubleshooting step, perform a hard factory reset on the Asus router followed by an initial manual configuration. Do not import a saved router.cfg file after performing a hard factory reset. Do just enough configuration to get the router online then test if the Visual Studio remote website access issue persists.

 

[Tech9]

Is there any particular reason why you (I assume) replaced your previous Internet router with the end of life Asus router?

@bennor, see post #3.

 

[bennor]

@bennor, see post #3.

Yes missed that. Still it's a 10 year old end of life router on the old 386.x firmware. Probably wise to give serious thought to upgrading to something newer for an internet facing router.

What ever the case, it sounds like some sort of configuration issue with the Asus router.

 

[DMoody007]

Morning All,

Agree on age of router. Just using what I had for now so I can work. New in box, free and instantly available collecting dust on a shelf. Didn't think it would be this hard. I can knock out Cisco, Linksys, Netgear, TP-Link, SonicWall, etc without blinking. But I went down the rabbit hole on this one.

I think I figured it out. Was experimenting with the Firewall and Network Services Filter in the router until the wee hours last night. I enabled the filter and put in two entries for the Allow List. My IP, the FTP port being used which was 2101, the remote server IP and the same port 2101 for UDP and TCP. The moment I applied, I was able to access the files via Visual Studio. I am assuming this is basically putting in a Bi-Directional rule in the firewall to allow this specific traffic. Would be nice if I could see the rules like a normal firewall.

Will try coding today and see if there are any hiccups. Thanks for your assistance to date. Will update at EOD if issue is resolved.

 

[ColinTaylor]

I am assuming this is basically putting in a Bi-Directional rule in the firewall to allow this specific traffic.

The Network Services Filter is a one-way rule, LAN to WAN.

As I understand it your FTP server is remote (i.e. somewhere on the internet) and not local. Therefore do not disable the router's firewall. The firewall already allows all outgoing connections.

The issue with FTP is that is requires a second "data" connection on a different (random) port. This is a problem when the client is behind a NAT device like a router. If you're using Passive (plain) FTP the router has a helper module that should detect the passive port and correct any NAT issues. If you're using Active FTP you'll have to manually forward the second port. If you're using encrypted FTP (i.e. FTPS) this presents additional challenges.