I have 2 wifi access points in my home network, I often can't reach internal IPs from one of them.
Example of problem:
Android Phone --> Access Point 1 --> NAS (using IP, no DNS): "Cannot reach network host" Android Phone --> Access Point 2 --> NAS (using IP, no DNS): Access works ok. It's the same behaviour trying to reach other machines, Kodi box, Raspberry Pi, DTR etc., not just the NAS.
However, SOMETIMES (inconsistently), I can access internal machines via Access Point 1.
Access Point 1 is my main internet router (BT Homehub 5).
Access Point 2 is my upstairs access point (DD-WRT), it's connected through powerline adapters back to the main router (via my 8-port switch)
DHCP runs only on my main router, DD-WRT forwards any requests to the main router.
Do routers or switches have a feature to block traffic from an end point if it looks like it was recently coming through another port?