ItCoder

You can try clicking Start now and continue in the following page, if it works it will enable access to MU (without losing access to WU). If it doesn't, nothing will happen. But it might help because it will download authcabs (they are related to checking for updates at least in MU).

Check if your patched wuaueng.dll is 1,xx MB or 2,xx MB. If it's 1,xx MB it's the 32bit version which won't work on 64bit systems. You can try putting it in SysWow64, but I don't know if it works.

Can you access https://fe2.update.microsoft.com/windowsupdate/v6/default.aspx?g_sconsumersite=1 with ProxHTTPSProxy?

Check if wuaueng.dll has a digital signature into properties. If it hasn't, it's already the patched version. If it has, it must be dated 2012. Check also if you have the same copy in C:\Windows\System32\dllcache. If not, install windowsupdateagent (but version 7.6.7600.256, 320 is not for XP) with /WUForce option. After that, patch wuaueng.dll both in System32 and dllcache.

This is a system error. Try running sfc /scannow and reinstalling Windows Update Agent. Tell me also if ProxHTTPSProxy shows a call to fe2.update.microsoft.com/v6/ClientWebService/client.asmx

You should click on Advanced on the last screen and put the IP address only into "Secure", leaving the other ones blank. The Proxy works only with HTTPS.

You should replace wuaueng.dll in system32 and in system32\dllcache, otherwise it gets restored. But the website should open anyway, only the scan should fail. Where does it exactly stop loading?

Check if you have Windows Update Agent 7.6.7600.256, and the patched wuaueng.dll (it's not signed by Microsoft). Check also if you have the WuRedirOverride keys. Once everything is done and you start a scan, you should have a v6-win7sp1-wuredir.cab in one of those folders

Look into the folders

Check into C:\winnt\softwaredistribution\wuredir if there is one file that contains fe2.update.microsoft.com

The installer is in English, but it installs in any language. You can try to see if it works, but then you have to reconfigure the system to work with your proxy (reinstall the Agent, add registry keys, replace wuaueng.dll with patched version, set your proxy in IE). That happens because redirection, in my method, is done on the server to allow Automatic Updates to work. Alternatively, you can try unregistering muweb.dll, uninstall IE6 (and IE5.5 if it gets restored), reinstall it and register muweb.dll again.

I've simulated this and Microsoft Update opened fine. Try my installer (https://1drv.ms/u/s!AsVjtW11rJfA3FQANrgg_QXRMgfx?e=7q2PhN).

Does it appear in IE's plugins list?

If Windows Update works and muweb.dll is registered, it has to work (tested). I once ran into an issue on Vista, regsvr32 didn't see muweb.dll anymore (and IE did the same). Try to place muweb.dll in a different location and register it again (mucltui.dll is not needed, as it's automatically installed at first run).

I created a GUI installer for my method using Legacy Update's one as a base. You can download it and view sources at the same link (https://1drv.ms/u/s!AsVjtW11rJfA3FQANrgg_QXRMgfx?e=7q2PhN). I've tested it on any version from 2000 to 7 and it works. Tell me if something doesn't.