There was a "Wireshark 2 preview" in the 1.12 Windows installers up to 1.12.1.
The name "Wireshark 2 preview" is a bit confusing. The only way in which it was a preview of Wireshark 2 is that it was built using the Qt toolkit, rather than the GTK+ toolkit, so that it had the new Qt-based user interface; Wireshark 2 was going to offer the Qt-based user interface as the default, with a "legacy" GTK+-based version also available. The rest of it was just 1.12.1, so, other than the UI changes, it offered no new capabilities that the regular GTK+-based 1.12.1 release offered. It didn't dissect any more protocols, it didn't have any bug fixes to protocol dissection that regular 1.12.1 didn't have, it didn't have support for capturing on any devices that regular 1.12.1 didn't support. It may have changed the way some statistics windows worked, due to the UI change; it may also not have had some statistics windows that the regular 1.12.1 version had if those statistics windows hadn't been converted to use Qt yet.
So there's really not much reason to use the "Wireshark 2 preview" version of Wireshark from the 1.12.1 installer.
The "Wireshark 2 preview" was removed in 1.12.2, because "Users wishing to try the Qt UI should use the 1.99.x installers.". The beta and release candidate versions of Wireshark 2.0 were numbered as 1.99.x; they, unlike the 1.12.1-based "Wireshark 2 preview", included changes to the Wireshark code not in the 1.12 releases, including new protocol dissectors, enhancements to new protocol dissectors, and so on.
However, those weren't the final Wireshark 2.0 release. The Wireshark 2.0 release included bug fixes that weren't in any of the 1.99.x releases.
So there's really not much reason to use the 1.99.x versions of Wireshark, either, even if they're available to download.
If the "guys on the Internet" were discussing the Wireshark 2 preview release recently, they're probably very confused; that release is from 2014, more than 4 years ago. If they were talking about it back in 2014, then they weren't confused, but you were mistakenly thinking it was something up to date that you should try to use.
Now, if by "interfaces" you're referring to the network interfaces supported by Wireshark, not the user interface, the version of Wireshark won't make any difference at all - 1.10.x, 1.12.x, 1.12.x "Wireshark 2 preview", 1.99.x, 2.0.x, 2.2.x, 2.4.x, 2.6.x, they'll all see the same interfaces. It's WinPcap that controls what network interfaces show up, and they're all using WinPcap 4.1.3.
The problem with your 3G modem is that it's ... (more)
Which version of Wireshark are they calling "Wireshark 2 Preview"?
Wireshark 2.0 was released in November 2015, more than 4 years ago. The preview releases, which had version numbers such as "1.99.9", came out earlier in 2015. I doubt that there's any good reason to want to use them.
There were also preview releases of Wireshark 2.2, 2.4, and 2.6, but those also came out a while ago.
The next Wireshark major release will be Wireshark 3.0; its preview releases have numbers such as 2.9.0. That preview release was announced on 2018-12-12 - but it's not supported on Windows XP.
The last version of Wireshark that we supported on Windows XP was Wireshark 1.10, released in June 2015. No 2.x version was ever supported on Windows XP, and 3.0 will not be supported on Windows XP, either.
@Guy, thank you for your kind reply. As I recall I have installed 1.12 version for win xp which came boundled with 2. Preview, I installed for tests. I was advised to go back to 1.10 version so uninstalled 1.12 and installed 1.10 Either 1.12 or 1.10 showed the same interfaces. Since I live on 3G usb dongle modem, I have installed recently USBPcap driver and was able to dump usb mouse's traffic to file and open the file in Wireshark. Since USBPcap driver run resets my usb modem I will try to select my usb modem as interface to learn more about Wireshark. In the above case USBPcap records usb traffic to a file and W. acts as a parser and GUI viewer.
Yesterday I have tried 2 of my TL-WN422G TP-LINK wifi usb dongles to connect to my wifi camera from ...(more)