Thanks.
I’ve had the traffic tab open in my browser for several hours (including the time I quoted from syslog above).
The TTN console says that my gateway was last seen <30 seconds every time I check.
I see traffic using tcpdump, but nothing that looks like RF packets. Just lots and lots of these:
15:55:14.263606 IP B827EBFFFE8FE3C3.w3.mjo.se.46418 > 52.169.76.203.1700: UDP, length 225
E.....@.@.Z.....4.L..R....E......'......{"stat":{"time":"2017-11-11 14:55:14 GMT","lati":57.69952,"long":11.95215,"alti":13,"rxnb":0,"rxok":0,"rxfw":0,"ackr":100.0,"dwnb":0,"txnb":0,"pfrm":"IMST + Rpi","mail":"ttn@falkviddholding.com","desc":"FHAB #1"}}
15:55:14.315056 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.46418: UDP, length 4
E.. .W@.-.7`4.L........R..~...................
15:55:16.868261 IP B827EBFFFE8FE3C3.w3.mjo.se.57710 > 52.169.76.203.1700: UDP, length 12
E..(..@.@.[.....4.L..n....D;.Q...'......
15:55:16.916195 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.57710: UDP, length 4
E.. ..@...6.4.L........n..;X.Q................
15:55:26.988264 IP B827EBFFFE8FE3C3.w3.mjo.se.57710 > 52.169.76.203.1700: UDP, length 12
E..(..@.@.Y.....4.L..n....D;.sW..'......
15:55:27.037768 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.57710: UDP, length 4
E.. ..@...4
4.L........n..{6.sW...............
15:55:37.118086 IP B827EBFFFE8FE3C3.w3.mjo.se.57710 > 52.169.76.203.1700: UDP, length 12
E..(.b@.@.XM....4.L..n....D;.0...'......
15:55:37.166704 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.57710: UDP, length 4
E.. .[@...-\4.L........n..,y.0................
15:55:44.255547 IP B827EBFFFE8FE3C3.w3.mjo.se.46418 > 52.169.76.203.1700: UDP, length 225
E....*@.@.T.....4.L..R....E..`...'......{"stat":{"time":"2017-11-11 14:55:44 GMT","lati":57.69952,"long":11.95215,"alti":13,"rxnb":0,"rxok":0,"rxfw":0,"ackr":100.0,"dwnb":0,"txnb":0,"pfrm":"IMST + Rpi","mail":"ttn@falkviddholding.com","desc":"FHAB #1"}}
15:55:44.309819 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.46418: UDP, length 4
E.. ..@.-.+.4.L........R..>h.`................
15:55:47.248299 IP B827EBFFFE8FE3C3.w3.mjo.se.57710 > 52.169.76.203.1700: UDP, length 12
E..(. @.@.T.....4.L..n....D;.S...'......
15:55:47.298212 IP 52.169.76.203.1700 > B827EBFFFE8FE3C3.w3.mjo.se.57710: UDP, length 4
The packet lengths are always 4, 12, 4, 12, 4, 255 and then it repeats