17 devices detected by find desktop missing about 5

GaoGao

Hi there,
Find desktop 1.3.0. 
My router shows 23 devices up and running but find detect only 18. All devices are on the same IP network, some wired or WiFi. Below the 192.168.1.104 is a Samsung Smart TV. Similar result using Find Android. Any tips? Thanks.

rooted

It's not unusual for a phone to hide from a Fing scan as they usually disconnect from WiFi to save power when the screen is off. What are the other devices not registering in Fing?

Robin_Ex_Fing

Thanks @rooted

The Fing App discovery will identify devices on a best effort basis, based on the information made available by the device, e.g. the MAC address. There are numerous reasons why the device might not be recognized correctly e.g.

- The DHCP server is not refreshing when speaking to your Fing. 

- Limited information being offered by specific devices. 

Also, I would like you to make sure all devices are connected to your network on which the Fing App is currently connected to. If you are connected to the 5ghz network and Fing is connected to the 2.4ghz network even though they all have the same name, you might not see the devices connected under the Device tab. And, if the router has multiple network interface which provides multiple frequencies(2.4Ghz and 5Ghz), and the devices are able to connect to multiple access points then you will see multiple names but only one will be active at a time and others will be greyed out. 

 

GaoGao

Hi @Robin, hi @rooted, thanks for you replies. Today my Fing desktop shows a blank screen, apparently a recurrent issue with the desktop App, so I can't re-check and see what other devices were not reported. @Robin Nevertheless in the example I show in my post the device I pinged is a smart TV running Linux. As I can ping it at the same time Fing scanned the network the smart TV is up and active. @rooted As far I understand, Fing Desktop uses ARP as a primary discovery protocol , so I am not sure what you mean by the 5Ghz / 2.4Ghz things: This is the physcial layer, the ARP/MAC is the Data link (and a bit of Network) layer, so it should not have any influence. I have devices on the 5Ghz, 2,4Ghz and wired. 

rooted

I didn't know if you pinged the phone at the time, but since you did it was certainly online. I'm not sure what's going on, I think what @Robin is more talking about is a lot of routers have multiple networks such as a guest network which can be on a different subnet. I see the phone you were pinging is on the same subnet so it's can't be that.

Could you try rebooting your router and scanning from your Android device since Fing Desktop is misbehaving?

I have had my router mess up the ARP table several times and a reboot generally fixes this if that were the case.

GaoGao

Hi @rooted
Thanks. This part of my network is flat, all on  the same subnet.  Unfortunately even after a reinstalling the Fing desktop the scan screen is still blank, so I can't redo the test until the blank screen is fixed.

Robin_Ex_Fing

Hi @GaoGao
We have caught the error for a white blank screen. Can you try to update to 1.3.1 and see if the issue persists?

GaoGao

Hi Robin
Thanks.
1.3.1 still have the same issue. Nothing obvious in the logs. The service log show

ERROR 2020/04/17 17:19:36.716 === fing agent 1.3.1 - www.fing.io ===

ERROR 2020/04/17 17:19:37.664 HeartBeatEngine | Unable to find a valid network interface

ERROR 2020/04/17 17:19:38.523 GeoIpChecker | GeoIp Lookup internet checker [ONLY_IP] <- error <Unable to resolve: No such host is known>
Could be because Find may have started before the IP configuration completed.
No error in the App log as far I can see. The Windows Event Viewer is as clean as expect (meaning not totally clean but apparently nothing related to Fing). My Windows version is 1909, fully patched, nothing too exotic running. 

Robin_Ex_Fing

Hi @GaoGao
Thanks for your feedback. Our developers have caught the issue and the fix will be released with future version of Fing Desktop. The reason for this error was a network discovery interruption and failure of UI rendering.

GaoGao

@Robin
Hi Robin, thanks for the new version I just installed it. I can see the devices list but it is still missing some devices, (7/22) here the MIA list:
MAC :  40:30:04:19:D1:B7  an old ipad 
MAC:  00:17:13:10:C1:1A  an ethernet-Wifi bridge
MAC:  D4:11:A3:43:64:01 an android smart phone
MAC:  C4:98:80:86:33:13 an iphone
MAC:  F8:59:71:42:9D:AC an lenovo laptop
MAC:  50:14:79:19:F2:2F a Roomba robotic vacuum cleaner
MAC:  A4:30:7A:5D:E2:FA a Samsung TV
I compared the active devices list from my router/DHCP server to the Fing list. NMAP ping discovery is doing a bit better missing only 3. 

Stay safe!

rooted

Are those devices on that bridge?

GaoGao

@rooted
All theses devices on the same broadcast network, all receive their  IP address from the router by DHCP, a broadcast protocol as ARP. So if DHCP is working all the devices should all be discoverable by ARP. I just sniffed a Fing discovery, I counted 32 ARP replies but the Find interface shows 23 devices. Of course it is possible than some of the devices were replying to another service than Fing, but pretty improbable. See attached: Marked in white text on a black background the devices that replied but not appearing in the Find devices list. Sorted by IP address, source of the replies removed for confidentiality reason. If useful Sniff file at your disposition in private message. 
Edited: The common point off the missing devices seems a slow reply to the ARP request.
Hope this helps

GaoGao

I found this in the Microsoft Event log, poping-up at each find start-up. MSVCR90.dll is a dll of the Visual C++ redistributable, the 2008 version, included in C:\Program Files\Fing\resources\extraResources\.

Level Date and Time Source Event ID Task Category

Error 27/4/2020 9:49:34 am Application Error 1000 (100) "Faulting application name: fingagent.exe, version: 1.3.2.0, time stamp: 0x5ea07133

Faulting module name: MSVCR90.dll, version: 9.0.30729.9619, time stamp: 0x5c4bd872

Exception code: 0x40000015

Fault offset: 0x0005beae

Faulting process ID: 0x1428

Faulting application start time: 0x01d61c6817d406b6

Faulting application path: C:\Program Files\Fing\resources\extraResources\fingagent.exe

Faulting module path: C:\WINDOWS\WinSxS\x86_microsoft.vc90.crt_1fc8b3b9a1e18e3b_9.0.30729.9619_none_508d9c7abcbd32b6\MSVCR90.dll

Report ID: 6eb1a251-b706-4f87-926c-1538e9384024

Faulting package full name: 

Faulting package-relative application ID: "

Robin_Ex_Fing

Hi @GaoGao

Thanks for the information. Can you please make the following 2 changes on the Fing Mobile App: 

1. Disable Reverse DNS Lookup 

2. Change the Maximum network size to match your network size. 

To do this: 

• Open the Fing app, ensure that you are on the Network associated with your Fingbox 

• Tap on the Avatar icon in the top-right corner 

• Choose 'App Settings' 

• Scroll down and go to the "Maximum Network Size" setting and select the size based on the number of devices connected to network in your house. 

 
 These changes should help with the issues in scanning.  

GaoGao

Hi @Robin
Thanks for your reply. I did what you suggested.

• Fing App (Android 10, 5Ghz Wifi), 16 device detected
• Fing Desktop Windows (5Ghz Wifi), 19 devices detected
• Angry IP Scanner Windows (5Ghz Wifi) , 20 devices detected
• Router, 25 devices marked as "Active". 

 

Robin_Ex_Fing

Hi @GaoGao
I believe you have a lot of IoT devices and those are the IoT devices missing from the list. Can you confirm the same? The Fing app and Fing Desktop does a quick scanning of device discovery and the IoT devices takes time to discover which gets skipped by the Fing App.

GaoGao

Hi @Robin
I have lot of IoTs indeed but I just performed another a sniff of the Find discovery process and, as in the wireshark screen capture I sent before, the common factor for a device not showing in Fing list seems to be a slow reply to the ARP request. Just right now Fing missed a laptop and the command panel of the home automation system, but found a vacuum cleaner robot. These two missed devices were indeed late to reply, 46 ms and 136 ms compared to about 10 ms for the reported ones.
Fing is nice but optional for me, I have other systems to manage my network. I am very keen to help Fing and grateful for your interest, but if you think it is going too far feel free to close this exchange. At the technical level I think the Wireshark trace and the slow ARP reply from some of the missed devices is the best clue, "behind the scene", about why Fing is missing them. I have of course no access to Fing internal technology and it is certainly more that a simple timeout issue, so I can't really going further, only your development engineers can. 

Robin_Ex_Fing

Thanks for the feedback @GaoGao I will pass on this feedback to our developers for review. Thanks again.

Ernest

New member: I got all of my 20 devices recognized today and now only two show in Desktop and all of them show in https://app.fing.com/app!  Anyone have any helpful hints?

Update:
If you desktop app shows only few devices click on the Word "All" right of center toward the top of the page.