Unifi LTE failover issue

1

OK have a strange issue when using the LTE pro unit in a fail over situation with certain devices on the network. We use this is a POS environment with a UCG Ultra and the U-LTE-Pro. along with a USW-Lite-8-Poe switch. The LTE device is connected to the USW switch for poe power.

Main wan goes down switches over to the LTE failover with no issues on almost all devices and switching back is the same thing. My problem is with certain payment devices which are android devices. Hardwired to the switch. When switching over from wan 1 to failover and back I get something like a heartbeat connection issue. The device is online I can see it online but when we try to communicate to the devices software to run a transaction we get an unresponsive commutation issue. How ever if we power cycle the payment device once its switch over to lets say failover it works fine. If we unplug the network cable and back in it works fine. And if we switch back to wan 1 we have to do the same thing to get them to work again. Manufacture is little to no help as all they say is that it is our problem not there’s really and maybe a latency issue causing the problem. Currently we are at a lost here on what to look at with this at this time.

2

Sounds like the android system is holding on to the state tables until it detects a network change or is power cycled. Not really sure how to fix that.

3

LTS_Tom’s diagnosis sounds right. The Android payment devices are likely keeping their TCP/IP state tables active from the previous WAN connection and not properly detecting the network path change when failover occurs. A few things worth investigating: check if the UniFi controller has ARP proxy or gratuitous ARP settings that might help signal the network change to endpoints, look at whether enabling a shorter DHCP lease time forces the devices to renew their network stack on failover, and consider whether the payment device manufacturer supports any keepalive timeout settings that could be shortened. For POS system vendors tracking which support channels generate the most inbound technical inquiry calls, Phonexa helps attribute those conversations accurately.