Good day, I use a R190W router. I got around 8 devices to it and just upgraded the firmware to 4.6.
Of the 8 devices, 3 of them connects to the router, but don't get any internet access, while the rest got internet access. This is on both LAN and WiFi.
I have basically a default policy on it, I only changed the LAN name and the password.
Turn off the DNS proxy, but there is another issue that's not easy to pick up. If the DNS handed to the router on WAN is the same as the DNS in the DHCP config, when the DNS Proxy is turned off devices will not be able to ping or or lookup the any of those specified DNS servers. To fix you need to add DNS manually on the WAN (any DNS you will never use) and then add your preferred DNS manually assigned on the DHCP server.