EC230-G1 AC1350 in Access Point mode drops the internet connection when client connects to it
So I have two EC230-G1 devices (it's not on the Model list, I picked a similar one), first one is on the attic, works in router mode, has an Internet cable connected to the WAN port, DHCP enabled, range 192.168.0.100 - 199. The second one is on the ground floor, configured as an Access Point, has a WAN port connected to the 1st LAN port in the router (first device), DHCP disabled.
Both devices have WiFi configured to the same SSID and Password, channels are set to Auto, according to the configuration they're working on different channels.
The issue is that when I'm going downstairs to the ground floor and my devices are switching to the WiFi from the Access Point they say that they cannot connect to the internet (not to the WiFi itself, the WiFi signal and strength is OK). My Mac says that it couldn't get IP assigned and has a self-assigned IP, Android devices show me exclamation mark and information No internet access next to the WiFi icon.
After a while (like 2-3 minutes), the issue fixes itself and devices get new IPs and are working correctly. The issue also doesn't occur when I'm on the ground floor and connect to WiFi from there - everything works fine. The issue doesn't occur when I'm going upstairs and I'm being reconnected to the router from the Access Point.
What I tried and it didn't help:
- setting the same WiFi channels
- setting Static IP of the access point within the DHCP range (192.168.0.100)
- setting Static IP of the access point outside the DHCP range (192.168.0.2, 192.168.0.254)
- enabling DHCP on the access point with different IP range (192.168.1.100-199)
There's also some suspicious WiFi setting called Enable Easymesh settings, however, I didn't mess with it as I couldn't find any reliable info about what it does.
I suspect some strange Firmware issues connected with DHCP in Access Point, however, it's a blind guess, also I couldn't find any firmware update for my device, also there's no any TP-Link support page for it.
What I'm trying to achieve is to have the same WiFi SSID on all floors in my house and have devices switching between them without dropping the internet connection for a long time.
It seems that the same issue happens for Archer routers: https://community.tp-link.com/en/home/forum/topic/186586 . Any ideas how to fix it?