Am I right to assume that when the receive windows are delayed by an additional n seconds, the backend also sends the downlink data to the gateway n seconds later? (It seems downlink data is currently always sent to the gateway 800 ms before the given RX1 or RX2 slot?)
In other words: I’d assume increasing RX_DELAY fixes half of the problem: it helps with slow uplinks (from gateway to TTN), for which the application server gets the uplink late and then does not have enough time to tell TTN if some downlink is needed. But I’d guess it would not fix slow response times (from TTN to gateway).
A good example of latency problems seems to be “OTAA ok, 12h later I get denied, reboot gateway –> OK again …!?” for which the OTAA Join Accept receive window is at 5 seconds after the Join Request, but still comes in too late for some 3G gateways.