@TP-Link_Deco 

This particular modem doesn't allow bridge mode unfortunately. I looked for it, but couldn't find any setting for it. But it got half-burned on a thunderstorm last Friday, so it's going to be replaced soon. I just don't know if it will be the same model or a different one. 

Maybe then I can know 

@TP-Link_Deco 

Regarding the DCHP settings, I think you should have 3 modes:

1. Smart DCHP (apparently fixed, as the Decos don't seem to be passing the real gateway information after a while)
2. "Standard" DHCP, where there's no attempt by the Deco to cover for the router. If it's a router issue, it can be know for sure
3. Static IP

@TP-Link_Deco 

Hello.

That modem had no bridge mode, but due to being partially fried due to a thunderstorm, it was replaced with a techicolot TG784n v3, and this one has a bridge mode, and it seems to play better with the "Smart DCHP" of my TL-WR902AC at least. The router was able to assign an IP to the travel router, which bodes well.

In any case, I do have a somewhat special feature in my network. One IPTV set-up box needs to be connected by ethernet. That actually was working with AP mode and the old router.

In any case, now I need to return the Devolo ones that I tried as replacement. They didn't work well with the set-up, and then get another set of P9s. But, is it possible to get the latest beta firmware for them? I don't mind testing it. As they are now, the lack of management capabilites is appaling.

@jpasan 

I've seen a similar issue with clients showing as having a WiFi connection but not being able to connect to the internet - or other devices within the local network. I've been trying to do a bit of investigation on this and maybe the following info will help in tracking the issue down.

First thing is that my config is Deco P9's in AP mode, main one linked to ADSL router and other two spread around house. At all times, they have the normal LED showing they are fully operational.

I initially suspected the SmartDHCP intervention that's mentioned in other threads - even when in AP mode. That would be annoying, as you can't configure the DHCP server settings to at least match what my ADSL router is offering in terms of network, gateway etc. Reason for thinking this was the issue is that I would see on the ADSL router log many DHCP log entries.

Normal pattern of DHCP log entries on the router is 

1) Recv DISCOVER

2) Send OFFER

3) Recv REQUEST

4) Send ACK

I would see the first 2 entries only but repeated many times which might be consistent with another device (e.g. Deco P9) responding to the DISCOVER more quickly, the client then has no internet as the gateway is wrong, so disconnects and tries again.

Test of this has been to move most devices on my network to static addresses - by which I mean a statically configured IP address on the client directly, as opposed to a fixed, but DHCP assigned address.

This has improved the situation in terms of log entries on the router - as you'd expect as most devices aren't doing DHCP any more - however, it hasn't solved the problem of devices showing as having a WiFI connection, but no internet connectivity.

There's not much I can do further, without delving deeply into this and doing Wireshark traces on a laptop if I can reproduce the problem reliably. However, a couple of other observations which might help.

1) The problem is primarily (but not certain it's exclusively so) on devices which are moved around the house. A device which is in a fixed location and should have a fairly obvious choice of Deco device with best signal tends to be fine. So a desktop PC, or a laptop sat on the same desk/table all day, tends to be fine.

2) I don't see the problem at all on wired devices - I have an 8 port LAN switch plugged into one of the Deco units, with TV, XBox etc plugged in using wired, rather than wireless connectivity. Again, these are fixed location devices so may just fall into the same category as observation (1).

3) The problem is definitely worst for devices which are moved around the home - mobile phones and tablets - although some seem to be affected more than others, but this is not obviously related to, say, age of device. A Samsung Galaxy S10 has few problems but a Samsung Galaxy A20e has many issues - both are 2019 models running Android 10.

4) It's client specific, not a Deco unit connectivity failure. i.e. with two clients sat next to each other, very close to one of the Deco units, getting a strong Wifi connection, one client might have internet connectivity but the other won't. Often if you disable/reenable Wifi on the broken client, it'll then have connectivity

5) Here's the really interesting one, although I've not done rigorous testing to verify it's reproducible..... A client has been seen to be working in one room, move around the house and transition to another Deco, fail to have internet but then when moving back to the original location, internet connectivity is working again (no need to disable/re-enable wifi).

From the last observation, I'd speculate whether this is an issue with hand-off from one deco unit to another. Perhaps it's a failure to update ARP entries or similar (reaching the limit of my IP network knowledge here!) such that maybe the network packets aren't sent back to the correct Deco unit so fail to reach the client. This would also be consistent with the DHCP issue seen initially - if the OFFER didn't reach the client, then it'll never issue the REQUEST but will retry the DISCOVER. That's probably a better explanation for that behaviour than the speculation around SmartDHCP activating in AP mode.

Hope this helps TP-LINK engineers or other users to get to the bottom of this.

@DrChris 

Many thanks to your insights.

My situation is similar. ADSL connection and the Deco P9s connected to it in access point mode.

But the results seem different. Mobile phones seem to work well around. One Huwaei P20 and another P20 Pro, experienced no issues. I don't remember now about my brother's Nokia 6.1.

The static IPTV set-top box, that was the only wired client in my network never experienced issues.

My work laptop that is static, that I turn on during the morning and only turn off during the evening kept working. My personal laptop in the same room that is used on other occasions also worked. My father's and brother's laptops that were not continuously on, were having the issue. Also when the Smart TV and Xbox that I have in the same room I'm working from, which are rarely used, had the same issue I gave up on the Deco's.

Worst of all is the only solution to be restarting the main Deco, because when that happens, the entire network collapses. The only devices that remain functional are the one still connected to the router's ports.

Since the devolo alternative didn't work for me, but at least they told me explicitly to exchange for a new kit from the retailer, or worst case scenario they would replace it themselves, since I've got this new modem, I'll give the P9s another try. Because to be fair, they did have awesome WiFi coverage. Finally a solution would cover the whole house.

If it's still not enough, I can still try the Huwaei Q2 Pro. Also hybrid wireless and powerline. That's my mine requirement.

@TP-Link_Deco 

Hello.

Thank you very much. I'll be waiting then.

Have a nice day as well.