Some more updates, I have booted in safe mode and the issue is still there.

Now, I was chatting with Nokia support for a good half an hour, conencted to the deco wifi, and the network kept ongoing.

But as soon I do my test of disabling/enabling the wifi on the nokia, starting youtube and play a [long] video, after 6-7 minutes disconnects.

So, small chatty network keeps it alive, streaming causes a disconnect (and you don-t even notice because the wifi icon shows ok, but anything trying to get anything from the net does not work and reports no connection).

Any help on this?!

I tried all combinations, using DHCP or fixed IP, with dhcp DNS or fixed DNS, and also tested all combinations of options of the deco, even disabling everything there to make it as non-mesh as possible, allways the same issue. And no QoS or other extra stuff setup ever, I kept it as simple as possible for now. And I did all the tests with the second deco powered off to ensure no interference. Yesterday I changed the LAN IP to 192.168.0.1 (similar to what I was using in the tplink wr1043nd, just in case), but the issue is still there. I will try that ping, but as I mentioned, when this happens, the apps complain they cannot refresh/access the net, while the wifi connection shows connected and looks fine. 

Yesterday I brought the same nokia 2.2 to my workplace where we a mesh cisco entreprise network, with two SSIDs and both in 5GHz and 2.4GHz (something very similar what the tp-link deco M4 provide), the nokia had no issues here. I also provided this feedback to nokia (so that at least it is registered in case somebody else has similar issues).

So, up to now these nokias have been connected to half a dozen networks (including one provided by 2 tplink wr1043nd v3: ISProuter - tplink as AP ssid0 - tplink as extender ssid1), the only one I have with issues is with the tplink deco(s).

I also asked for tplink support (Portugal), with screenshots of several steps of the wifi tests (with the nokia booted in secure mode, just to be sure nothing was interfering, also as nokia support requested) and last tplink support email mentioned they were handing over all the info to the engineering team (I also provide the link to this forum thread, so that they can keep an eye on it as well).

I think the only way here would be to capture the network traffic between the deco and the nokia 2.2 to analise, but I have no idea on how to do it from either side...

Maybe tplink can buy a nokia 2.2 (they are cheap) and do their own lab tests, if they find that the issue is with android one, provide the feedback to google/nokia, if they find on the tplink, just update their firmware.

Locally I think there is no tiket number, but the portuguese technician is passing my feedback to another non-portuguese tp-link technician (that I added as administrator already to my deco network) and vice-versa, "translating" their requests back to me, so this is ongoing.

Victor

@Kevin_Z, now is being handled by tplink support #275699.

Latest tests with a tcpdump run on the tp-link and ping tests on the PC to the nokia 2.2 shows that the wifi stays connected, but pings do fail for X minutes each X minutes, and eventually the nokia gives up and shows wifi without internet. I think that after some time it will reconnect (the damage is done however) but usually a manual disconnect/connect to wifi solves it, but only for x minutes untill the issue re-appears again, very annoying.

And apparently somebody else has similar issues issues with different androids than the nokia 2.2, with the exact symptoms I have, with connects+disconnects each X minutes, eventually the wifi shows connected with no internet and fails - thread here https://community.tp-link.com/en/home/forum/topic/172760

My last test would be to be able to force the channel to a specific one and change the width (from the default 40Mhz?) to 20Mhz in the 2.4Ghz, but there is no way to do that in the firmware (this should be there, to be able to allow automatic or manual channel/width on 2.4Ghz and channel on 5Ghz - enhancemente request here?), hopping that support helps me on this.