OpenWRT and VLAN

I use a NanoPi R2S as my back up router.  Another day, I was setting it up from scratch.  I set up VLANs on it as I did before, however, I couldn't get an IP from any of the newly created VLAN networks.  I have checked the VLAN set up over and over again, and compare it with setups found in YouTube videos.  Everything seems in order.  Then, I check my switch, and again everything seems right too.  I was puzzling for a few days.

Few days later, I looked at the settings again, still couldn't see anything wrong.  Then it dawned on me to check the firewall settings, and the problem was indeed an firewall issue.  I may be wrong, but I think the own default was

input -> accept

output -> accept

forward -> reject

where as the new default is 

input -> reject

output -> accept

forward -> reject

As I highlighted, the culprit for my problem is the change to the input default setting.

INPUT governs traffic originating from devices in the zone that has its final destination on the router. Examples for this would be DHCP requests or DNS lookups

With input set to reject, computers on the network cannot talk to the router, i.e. getting access to the DHCP etc.  Hence, my computer appeared as having problem to join the network.

Simply change the input to accept, the problem fixes.