In the category of "I can't believe I still have to worry about this in 2023" 

comes an unfortunate discovery I made recently when setting up a network 

for a local non-profit.  The Inseego FX2000 5G router looked like a nice 

product, it supports OpenVPN out of the box, flexible firewall rules, etc.

What I did *NOT* expect from a device made in 2023, and didn't think to 

ask about ahead of time, is whether it supported classless routing.

Setting the unit up, I discovered the hard way that the developers are 

apparently still working from 1989 textbooks.  The only netmask the 

router will accept for a 10.x.x.x. subnet is 255.0.0.0.  Absolutely refuses 

to accept a different length netmask.

Even the user manual reflects the inherent classful assumption:

"

IPv4 

IP Address: The IP address for your FX2000, as seen from the local network. Normally, you can use the default value. 

Subnet Mask: The subnet mask network setting for the FX2000. The default value 255.255.255.0 is standard for small (class "C") networks. If you change the LAN IP Address, make sure to use the correct Subnet mask for the IP address range of the LAN IP address

"

So, before anyone else makes the same mistake I did, I thought I'd give the 

community a heads-up to avoid the Inseego line of 5G products, as they're 

woefully behind the times in their understanding of IPv4 subnetting as it 

exists in 2023.  ^_^;

Thanks!

Matt