The intended setup is: optical wire -> modem -> router: wan interface (DHCP client) -> lan interface (DHCP server) which is linked to wifi -> Android/iOS/Windows clients.
I am trying to set up a wifi hotspot for a dozen clients. The problem currently is that after 2-3 hours or sooner if there are close to 8 clients connected, the wifi connection drops. Android phones are stuck at "Obtaining IPs" and my Windows 10 laptop shows as connected, but can't even access router GUI control panel (192.168.0.1). I haven't checked for SSH yet. After this happens, I can still use the internet and access the GUI control panel, if I connect via cable. Wifi works again only after rebooting.
What I've done during my last attempt to fix the problem:
Set up regional settings, where I saw them.
Removed ipv6 wan interface and IPv6 ULA-Prefix.
Unchecked the authoritative DHCP flag.
Changed the number of leased addresses (start 50, limit 150). The lease time is 12h.
Set up password for the network.
The rest are factory defaults.
I am new to OpenWRT and have to do with what I've got atm. I wasn't able to do extensive RTFM and network research due to current circumstances. Please, advice, what logs can be useful in figuring out the problem. I have only used the GUI control panel so far, but currently looking into SSH too.
It is not quite clear if you're running the preinstalled OEM firmware (which might identify itself as OpenWrt, but probably is quite far away from it, using the vendor SDK and a semi-proprietary kernel with vendor wireless drivers) - or vanilla OpenWrt as released from openwrt.org. In the former case there isn't a whole lot we could help with, as the vendor wireless drivers have a pretty different behaviour than OpenWrt's (mainline-) mt76.
The firmware is probably modified by the World Vision (the OP has a typo). I don't think there were major modifications, added brand name at the top of the administration panel. I forgot to include it, but here is the info from the GUI:
At this point as slh already hinted,
Since your device is using a modified software, not a standard OpenWrt firmware,
and even the basic login process to the router's menu is different...
Support is not possible.
A typical OpenWrt menu has the following:
Password: default does not have any password
You will need to check with your ISP for such information if OpenWrt default username and blank password does not work.
As for trying to access the router's menu via SSH,
You would still need the username and password.
Login screen was default, as you describe it. The default username was "root" and no password. The only difference is the address being 192.168.0.1 instead of ..1.1. I have set up a password and successfully logged in via SSH using Windows Powershell.
Even assuming we were talking about genuine OpenWrt 14.07 (and not the proprietary vendor SDK), it doesn't make the slightest sense to debug 8 year old rt2x00/ mt76 drivers. Quite a few pretty nasty bugs have been fixed in rt2x00 - and mt76 is improving massively every few weeks.