MaryJo Foley (a "she" not a "he"....although you might not be able to tell from her photo) is one of the biggest fans of Windows 10 you will ever read and listen to. She regularly covers MS at the both the consumer and enterprise levels. I have been following her writing and watching her for years on Twit.TV with Leo Laporte and Paul Thurrott (formerly of Windows Supersite, not Thurrott.com). If you knew anything about her writing and her history, you'd know she's a literal shill for MS. She's an insider's insider, attends every MS event, and while she lives on the East coast, is a regular visitor to Redmond and the MS campus. She's a huge supporter of Satya Nadella, and absolutely loves Windows 1o. She's been very upfront about her own e-mail issues experienced with the upgrade she did. She is the first to admit her experience has been extremely atypical.
Her story of her upgrade from Windows 8.1 to Windows 10 RTM (Build 10240) has been well documented from day one. Her biggest problem is that she is relying solely on an upgrade of Win10 from 8.1, and she has NOT done a clean install. She and Paul Thurrott have discussed this a lot on their weekly show on Twit.TV (Windows Weekly), and she's been reporting regularly on her travails with her e-mail and her Win 10 upgrade.
The issues that she says have been experienced by some people with the Windows Store aren't issues that are mission critical errors. They involve signing into the store and not being able to download an app. MS essentially has resolved such issues for the most part.
My biggest problem with Windows 10? Seriously, it is with Microsoft Solitaire Collection and the Daily Challenges. I find that it is difficult to log into the X-Box App and thus my scores don't update from one machine to the other. But my issues have only been with Build 10532, which is an Insider Preview Build, not the RTM Build (10420), which has none of those issues.
Again, Mary Jo should do a clean install. It would solve her issues.
And as far as "having to install apps all over again" I too used to think that was some big deal. But I find that I use far fewer apps and programs than I had installed in Windows 8.1 or earlier versions. Frankly, doing a clean reinstall was a great excuse to clear out all the crap that I haven't used in months, and sometimes years and years. Really, I use Word, Word Perfect, Thunderbird, several browsers, maybe some html editing programs, FileZilla, VLC, WordPad, Notepad, Adobe Pro, and not a whole hell of a lot else. Pretty easy to reinstall all of those programs in about an hour, and all of my data is backed up on data drives and my NAS drives, so reinstalling the OS really never touches that stuff.
In short, it's a lot easier to do a clean install than you may think. And if you haven't used a program in the past 6 months, you're probably not likely to be using it any time soon. And if you find you do need a program, well, everything can be found somewhere to be reinstalled when you need it, either locally on data drives, or on the net.
Lastly, you absolutely should get the latest driver for your NIC from the manufacturer's own website, and install it (first uninstall the device and select "delete the driver"). Then reboot and allow the new driver to be installed, and then reboot again. Finally, in order to prevent a bad driver from being reinstalled, you need to run "WuShowHide.cab" (just Google that), and "hide" any updates that Windows Updates shows as being available for your NIC. If you don't hide them, Windows will automatically force an update to your drivers and will reinstall the old/defective driver that may be contributing to your problems.
But once you update the driver, there's really no need to configure anything if you're using TWC cable internet. Just either set your router to get the DNS automatically from your ISP or input the DNS servers you want your router to use. Should work like a charm.