My roommate and I each have a 20S. We've paired the devices, and she can connect to me by pressing once on the jog dial, but I cannot connect to her doing the same (I hear the "intercom failed" message after doing so). This has been consistent for several months and across firmware versions (we're at the latest version now) — if we get disconnected due to distance, she has to be the one to press the jog dial to reconnect. Any ideas?
I had that issue a few times, and the problem was different each time.
The first time I had factory reset my headset after troubleshooting a different problem with Sena, but my riding partner had not. After doing that, I was unable to pair with his headset again....however he could still open an intercom to mine. My guess as to what happened is that his headset "remembered" whatever security handshake was made when the two units were paired and it was still valid....so when his headset reached out to mine to connect, my headset said "ok". The pairing would fail because his headset thought they were already paired so it would refuse to pair again. The solution to this was to go into the app on his phone and tell his headset to forget the pairing, and then repair. That fixed the issue (I also could have factory defaulted his headset but then it would have lost his other pairings).
The second time....I had paired to a different rider, and they had been put into a different "slot". I finally figured it out after lookint at the app, they were in slot 3, but I thought they were in slot 4....so I was trying to connect to the wrong person when I pressed the button 4 times. That was entirely user error.
The last time was also user error. A couple I was riding with (both with 20s's) had accidentally put their intercoms on each other's helmets. I was on a grocery run with one of them and the other stayed behind in the hotel. We pulled over and figured that out and when we got back to the hotel they just swapped the units back to the correct helmets.