diff --git a/Common/Common.vcxproj b/Common/Common.vcxproj
index a4b75fd2bc..85d534469d 100644
--- a/Common/Common.vcxproj
+++ b/Common/Common.vcxproj
@@ -294,6 +294,7 @@
     <ClInclude Include="..\ext\aemu_postoffice\client\log_impl.h" />
     <ClInclude Include="..\ext\aemu_postoffice\client\mutex_impl.h" />
     <ClInclude Include="..\ext\aemu_postoffice\client\postoffice_client.h" />
+    <ClInclude Include="..\ext\aemu_postoffice\client\sock_impl.h" />
     <ClInclude Include="..\ext\at3_standalone\at3_decoders.h" />
     <ClInclude Include="..\ext\at3_standalone\atrac.h" />
     <ClInclude Include="..\ext\at3_standalone\atrac3data.h" />
diff --git a/Common/Common.vcxproj.filters b/Common/Common.vcxproj.filters
index e61574cc5d..a8911742a6 100644
--- a/Common/Common.vcxproj.filters
+++ b/Common/Common.vcxproj.filters
@@ -719,6 +719,9 @@
     <ClInclude Include="..\ext\aemu_postoffice\client\postoffice_client.h">
       <Filter>ext\aemu_postoffice</Filter>
     </ClInclude>
+    <ClInclude Include="..\ext\aemu_postoffice\client\sock_impl.h">
+      <Filter>ext\aemu_postoffice</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="ABI.cpp" />
diff --git a/Core/Config.cpp b/Core/Config.cpp
index f4aab08ee1..8c0d098799 100644
--- a/Core/Config.cpp
+++ b/Core/Config.cpp
@@ -464,7 +464,9 @@ static int DefaultGPUBackend() {
 		return (int)GPUBackend::OPENGL;
 	}
 
-#if PPSSPP_PLATFORM(WINDOWS)
+#if PPSSPP_PLATFORM(UWP)
+	return (int)GPUBackend::DIRECT3D11;
+#elif PPSSPP_PLATFORM(WINDOWS)
 	// On Win10, there's a good chance Vulkan will work by default.
 	if (IsWin10OrHigher()) {
 		return (int)GPUBackend::VULKAN;
@@ -1494,13 +1496,20 @@ void Config::PostLoadCleanup() {
 		g_Config.iCpuCore = (int)CPUCore::IR_INTERPRETER;
 	}
 
-	// This caps the exponent 4 (so 16x.). No hardware supports more anyway.
+	// This caps the aniso level exponent to 4 (so 16x.). No hardware supports more anyway.
 	iAnisotropyLevel = std::clamp(iAnisotropyLevel, 0, 4);
 
-	if (iGPUBackend == 1) {  // d3d9, no longer supported
-		iGPUBackend = 2;  // d3d11
+	if (iGPUBackend == 1) {  // d3d9, no longer supported. Fall back to D3D11.
+		iGPUBackend = (int)GPUBackend::DIRECT3D11;
+	} else if (iGPUBackend < 0 || iGPUBackend > 3) {
+		iGPUBackend = (int)DefaultGPUBackend();
 	}
 
+#if PPSSPP_PLATFORM(UWP)
+	// Enforce D3D11.
+	iGPUBackend = (int)GPUBackend::DIRECT3D11;
+#endif
+
 	// Set a default MAC, and correct if it's an old format.
 	if (sMACAddress.length() != 17)
 		sMACAddress = CreateRandMAC();