@Sunshine 

Hi.  I bought it in February this year (Amazon UK - no reason to suspect it is bootleg),  and installed it pretty much straight away. Interestingly the device on my order is an AC1200 but the web page insists its a VR400 - perhaps they are the same.  Anyhow...

When the device name leaks away, sometimes it reverts to that before I modified (the "given name" I assume; other times it says "unknown".

U have never tried the tether app before - will load it up and see what I can establish. Hitherto I have only ever managed routers/modems via a browser interface - swith total success.

Edited to add an answer inadvertently missed: I first noticed this after editing several tens of names. It is possible that it started straight away - the effect is not predictable, and it may go a day or two without my noticing an issue. On other occasions, I'll name (or rename) an alias, which will write in - but another will at the same time or very shortly after revert. I have only difinitively proved this by making a list of what I'd renamed - I think I suspected some weeks ago but have only recently collected evidence.

I will revert in a bit after trying the tether.

@Sunshine 2nd reply as promised

I duly downloaded the tether app.

When I first logged in to the VT400 on tether, the aliases that had reverted in the browser duly showed the native names in Tether.

I renamed a (reverted-to-native) alias in Tether. Logged back in to the router in the browser, and the renamed device was correctly showing in the browser client list, but predictably (by me) another had popped to "unknown". I logged back in in tether and corrected "unknown" to the preferred name. I went around this rigmarole twice more, but the last time when I scrolled the list in the tether app all seemed well.

I logged back in in the browser - and all seemed well in there too - for the first time in a long time.  I know not how, but this does seem to have proved to be a work-around. Was this what you expected to happen? Should I subtlely rename a few more of these aliases from within tether to provide some more buffer space somewhere?

I spoke too soon.

I thought I'd just log in on the tether - and found another had reverted. I corrected it - on the tether - and in so doing, another reverted to native. 

I corrected that - still in the tether - and yet another reverted to native - still within the tether app.

I now conclude - following a false start - that it matters not whether a browser or tether app is used to rename peripherals, they randomly revert to native and/or "unknown" on an infrequent basis. The more aliases that have been renamed, the more likely this is to happen.

Edit - I have just done another 10 renames. There are a few of the sixty-odd clients that are much more prone to reverting. I have to believe there is too small a stack somewhere and it is overflowing. I just hope the process doesn't have a payload. I will stop chasing my tail pending a further response from TPTB. Thanks.

And another clue (and possibly a different problem).

When I log in (browser or tether), the client count as it first appears on the log-in screen is usually about what I'd expect - 15 or thereabouts on WiFi and another 46 or more wired. However, if I click the "wired" icon to see the list of wired clients (in pages of 5 on the browser) the displayed client count immediately drops to a smaller number - upper thirties or very low forties). Refreshing the browser page restores the larger number - which drops again when I try to look through the detail.

This problem remains.

I left it (without reasserting my preferred names) for a full month. It seems to be eating slowly away - though not at the first few tens which are permanent. It does seem to be that the later ones are more volatile - I still suspect a stack size issue - and still hope that it has no other knock-on effect (which is the main reason I am no longer attempting to put the wrong names right).

Anyone from TP-Link looking in here?

@Sunshine Do I need to log this as a formal issue somewhere? It needs investigating and confirming either as an inconsequential bug or fixing (or both). If there are latent conswquences (other than inconvenience of names going native) it's worth knowing surely?