I think you also have to log back in if you change IP addresses. I think it remembers two IPs. My IP at home rarely changes, but my work IP can change when they reroute things and I often have to re-login after a work outage/repair.
Agreed. When I am only going between my phone and my work, I rarely have to log in (same IP on my phone?). When I log in on my PC at home, then I end up re-logging in to all 3.