diff --git a/src/libraries/System.Net.Mail/Directory.Build.props b/src/libraries/System.Net.Mail/Directory.Build.props
index bdcfca3b543cbb..4784967b7f86ac 100644
--- a/src/libraries/System.Net.Mail/Directory.Build.props
+++ b/src/libraries/System.Net.Mail/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.NetworkInformation/Directory.Build.props b/src/libraries/System.Net.NetworkInformation/Directory.Build.props
index 63f02a0f817ef2..ce244cbea56199 100644
--- a/src/libraries/System.Net.NetworkInformation/Directory.Build.props
+++ b/src/libraries/System.Net.NetworkInformation/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.Ping/Directory.Build.props b/src/libraries/System.Net.Ping/Directory.Build.props
index 63f02a0f817ef2..ce244cbea56199 100644
--- a/src/libraries/System.Net.Ping/Directory.Build.props
+++ b/src/libraries/System.Net.Ping/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.Requests/Directory.Build.props b/src/libraries/System.Net.Requests/Directory.Build.props
index 63f02a0f817ef2..ce244cbea56199 100644
--- a/src/libraries/System.Net.Requests/Directory.Build.props
+++ b/src/libraries/System.Net.Requests/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.Security/Directory.Build.props b/src/libraries/System.Net.Security/Directory.Build.props
index 63f02a0f817ef2..ce244cbea56199 100644
--- a/src/libraries/System.Net.Security/Directory.Build.props
+++ b/src/libraries/System.Net.Security/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.Sockets/Directory.Build.props b/src/libraries/System.Net.Sockets/Directory.Build.props
index d68d22c1b917f8..ce244cbea56199 100644
--- a/src/libraries/System.Net.Sockets/Directory.Build.props
+++ b/src/libraries/System.Net.Sockets/Directory.Build.props
@@ -3,5 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/libraries/System.Net.WebClient/Directory.Build.props b/src/libraries/System.Net.WebClient/Directory.Build.props
index bdcfca3b543cbb..4784967b7f86ac 100644
--- a/src/libraries/System.Net.WebClient/Directory.Build.props
+++ b/src/libraries/System.Net.WebClient/Directory.Build.props
@@ -2,5 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
+    <IncludePlatformAttributes>true</IncludePlatformAttributes>
+    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
\ No newline at end of file