Can't Save IP Settings. Check one or more settings and try again.

For anyone who comes to this page with the same issue, and also finds that the information lacking clarity:

M$, in its infinite wisdom, changed one small-but-important aspect of manually configuring TCP/IP settings for IPv4 in Settings in Windows 10 from the way everyone everywhere has been doing it since Windows 3.1 (AFAIK).  Instead of setting the "netmask" or "subnet mask" (e.g., 255.255.255.0), in its place you need to enter the "subnet prefix length."  As the OP essentially asks, since most everyone who communicates TCP/IP settings to consumers provides the subnet mask, why, in the name of all that is holy, is Windows 10 now asking for something for which the general population has to search the Internet for the translation?  Thankfully, things haven't changed when looking at TCP/IP configuration in Adapter Settings, but you have to dig to get to that anymore.

[OFF SOAPBOX] 

So, to help those in need of finding the translation, here's a page I found that helped me just now.  From the table about 1/3 of the way down the page, just look for your subnet mask in the "Subnet Mask" column, then use as your "subnet prefix length" the number in the "CIDR Prefix" column, but without the leading "/" (e.g., 255.255.255.0 would translate to 24, not /24).

Cheers and good luck!

EDIT 6/25/21: I guess the link I included in my original post got wiped out, and I don't have a record of it.  Here (hopefully) is a link to an IPv4 CIDR chart; same concept: use the CIDR notation (without the "/" in front) that corresponds with your subnet mask:

https://www.meridianoutpost.com/resources/articles/IPv4-CIDR-reference-sheet.php

For anyone who comes to this page with the same issue, and also finds that the information lacking clarity:

So, to help those in need of finding the translation, here's a page I found that helped me just now.  From the table about 1/3 of the way down the page, just look for your subnet mask in the "Subnet Mask" column, then use as your "subnet prefix length" the number in the "CIDR Prefix" column, but without the leading "/" (e.g., 255.255.255.0 would translate to 24, not /24).

https://www.meridianoutpost.com/resources/articles/IPv4-CIDR-reference-sheet.php

Thank you! Although I think most people can just put in 24 without having to look at the chart.

What a wildly stupid change to the basic manual IP config.

Have a look at this post. It deals with a similar problem.

https://answers.microsoft.com/en-us/windows/forum/all/cannot-set-dns-server-in-ip-configuration/a1a853ae-f3f6-4796-a3c8-d25ca5833966

Thank you so much. This worked perfectly and this time I wrote all the settings down!

Hi! My name is Anderson Souza. I'm an Independent Advisor and a Microsoft user like you, I'll be glad to help you today.

Really, Subnet Mask and Mask Length are different ways of informing the same thing. I believe that most home Windows users do not need to know the intricacies of the TCP / IP protocol, and most of the time use automatic DHCP configuration.

But your suggestion is always welcome, feel free to give your suggestions for improvement to Microsoft through the appropriate tool for this, the Feedback Hub.

For complete information on using this tool check the link below:

https://support.microsoft.com/windows/send-feed...