@canalrun 

Same here, different router, an Archer A20.

I also have NEW VIEW problems occasionally (USB External power 4TB drive connected to the router) presenting an Error 52.

Try NET VIEW on your W10 PC in a CMD prompt, does that work?

I have to suspect Win10 or possibly the router?

However, I can't find anything Googling like this?

I did find one that said you had to run PING on the .255 IP Address to populate the list on your PC, and ARP -a.

I tried this,

C:\>ping 192.168.0.255

Pinging 192.168.0.255 with 32 bytes of data:
Reply from 192.168.0.122: bytes=32 time=184ms TTL=64
Reply from 192.168.0.122: bytes=32 time=96ms TTL=64
Reply from 192.168.0.122: bytes=32 time=101ms TTL=64
Reply from 192.168.0.122: bytes=32 time=106ms TTL=64

Ping statistics for 192.168.0.255:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
    Minimum = 96ms, Maximum = 184ms, Average = 121ms

and I did get ONE more device in the list. However, I have a some IoT's that didn't show. Still, checking against the DHCP list, it appears I didn't get all of them?

@IrvSp  Thanks for the reply.

Yes, I also found that one needed to ping the ….255 address before issuing an "arp -a". But it still only shows the 2.4 GHz band clients, none of the 5 GHz band clients.

I'm just guessing, and I probably have the terminology wrong – I think it might have something to do with the fact that the router implements the 2.4 GHz band as one interface and the 5 GHz band as the second interface. The arp command only looks at the first interface???

I wonder if there is another way to get the client list from the router programmatically. Do you know if the router responds LAN HTTP Get commands?

@canalrun 

Yes, but it isn't PRETTY and might not even be completely possible?

There IS a GETMAC Windows command...

See https://www.windows-commandline.com/get-mac-address-command-line/

However, to get a list, it could be a PAIN as the only way to 'sneak' onto a remote device on the LAN is to be allowed to access it. Either the device would have to have NO requirement for a User ID and Password, or you have to have permission/account on that device. Of course many will not honor the command.

If you wanted to do it, build a CMD file that does 252 iteration incrrementing the IP Address last octet by 1 starting with 2. Write to a file, and then scrape the file for IP's that responded....

I don't even know if an IoT would respond at all?

Could also programmitcally open a browser, log onto the router, get to the DHCP page, 'scrape' that, and go on until you got them all... that too would be a major undertaking I'd think?

This program (costs money) might work and do that as well, https://lizardsystems.com/find-mac-address/

Thanks @IrvSp  I will take a closer look at this stuff.