Problem about transmit error and ack timeout?

Hi, I have 3 Lima device ( i call A, B, C) config in mesh mode using batman-adv. All of them in short range so A <-> B B<->C and C <-> A. Pc connect to A, I open 2 cmd tab to ping from PC to B, C. When C down suddenly (loss power), ping msg from PC to B is timeout in some seconds, but when call reboot C, ping from PC to B is alive. After a long time check, i found that when C down suddenly, packet from A send to B is error. This problem is clearly when send more data ( i think send more data make tx queue full when C down) or increase config distance of wireless (to increase ack timeout). In case send more data or increase distance option, sometime ping msg from PC to B loss in > 60s.I expected that when C down suddenly, ping from PC to B still alive. Anyone can tell me why A send error when C down suddenly? And How i can reach to my expect.