Sideband can reach 0 peers

[radio-miskovice]

I don't understand how this works.
I run a rnsd in local network and Sideband on Android device. When I started Sideband, connectivity status said "Local - using wlan0" and "1 reachable peer": I suppose the reachable peer was rnode running in the local network. After a while I tried to send a message to a friend, to a verified (tested previously) destination. The message failed and now it shows "0 reachable peers" - but the rnode is still up and running... How is this possible? The rnode is open i.e. configured as transport node.