Facing issue to push downlink


I am unable to push downlink to my class A LoRa end device from chirp stack LNS.

For this, I am using v4 chirpstack gateway OS image (full version) provided here.

I am using RAK7248 LoRaWAN gateway for this purpose and have configured it to use us915_1 band. This gateway uses RAK2287 as radio shield.

I tried to push downlink using queue tab in applications window of chirp stack LNS GUI.
End device is configured for US915 region.

I am unable to receive any downlink on my end device.

I have also observed that device is unable to join network sometimes and if it does, it takes longer to join and number or retries to join network.

Once network is joined , I am able to see uplinks on chirpstack LNS but downlink still doesn’t work in this case.

Can someone please help what might be going wrong here ? Have I missed any configuration for US915 or misconfigured anything?

Any help will be highly appreciated.

Thankyou in advance .

What is this device and how do you know the problem doesn’t lie with it?
Do you see that your downlink is being sent in Chirpstack and the ACK from the gateway? You could buy a $25 SDR dongle to confirm that the gateway really sends the downlink (I’m just telling you what I would do).

Slow join accept is usually from frequency mismatch between server, gateway and node.