@Waterkeeper 

Sadly, I think they gave you the wrong information. V2 does not seem to accept the V3 firmware file for update. I get an error.

@Waterkeeper Sadly, the information you received does not seem to be true.

I just tried upgrading it with the V3 firmware, but I get an error. I don't think that the V2 switch will accept a V3 firmware. I even tried changing the name of the file, to no avail.

The firmware file must have some flag to identify it as a V3 specific file.

Confirmed, it worked and I noticed that it changed the hardware version to 3.0 as well, which is interesting.  So far so good.

Ahh, I just realized that I did this on a 52TS instead of a 28PS as the OP had indicated.  With that said, I do also have a 28PS on version 2.0 that could be upgraded as well. 

I plan to chat with support next week to see if that one would also be eligible to upgrade to the 3.0 firmware and I will post back with an update.  

EDIT: I didn't see the replied until I posted this.  I am sad to hear that it is not working for you.  I still plan to check with them next week and see what they say.  We'll see.

@Malaquias

You are indeed correct.  I just chatted with TP-Link support and they confirmed it.  They did say that they will send my information to their R&D department.  Should I ever hear anything back from them I will update this post.

Here is the transcript from my chat with them:

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TP-Link: Agent Bryant_SMB is at your service and hope the service will be satisfactory to you.

TP-Link: Good day to you! We will be glad to help you out with your inquiry.
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Me: Hi there!  I have a T1600G-52TS V2 switch.  The other day I chatted with a TP-Link rep and they told me that it is equipped with the same chipset as the V3 version, so I can upgrde to the V3 firmware.  I tried that over the weekend and it worked perfectly!

I also have a T1600G-28PS V2 switch, which also does not have any firmware available for it on the website.  There is a V3 firmware update available for this one as well.  Is it possible to upgrade this model using the V3 firmware?
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TP-Link: hi *********
hold on please
let me check the information
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Me: Sure
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TP-Link: Sorry i have checked the information, You cannot upgrade the firmware of V3, they are not compatible
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Me: Ok, good to know.  Do you know why there is no firmware section available on the support page for V2 of this model?
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TP-Link: may i know which country are you located in ?
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Me: USA
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TP-Link: okay
let me check
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Me: Thanks
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TP-Link: I just checked the official website, there is indeed no V2 firmware, but to be honest, I don’t know why the official website does not
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Me: Ok.  Do you know if there is any type of tier 2 level support where I might be able to get more information on that?
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TP-Link: actually I'm the L2 support
** They inserted a blushing face emoji here, lol **
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Me: I see.  Well, thank you for your assistance.  I hope that they can rectify that at some point.
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TP-Link: You are welcome.I will also transfer your information to our R&D department
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Me: Thank you.

@Waterkeeper  don't hold your hopes up. My local support person also took this up the chain of command, and he got the reply that it isn't possible nor will it ever be. The V2 is end-of-life, and the chipsets are incompatible.

@Malaquias Ok, good to know.  Thanks.

@Waterkeeper 

... and it did not worked :)

so, no, we could throw our v2 switches

say hello to "support" when you next time chat with them :) they are writing nonsence

Hello again,

So my V2 is EOL then... which is sad.

Any idea how to tell what version i am buying online ? any tags or stickers should say V3 ? or i assume the latest hardware this year being 2021-2022 will be V3 right ?

thanks guys