some computers show as Offline when they're not

I'm using TV ver 15.1.3937.

I have two Windows 7 computers ALIEN1 & ALIEN2.  Both have TeamViewer installed.  I’ve used TeamViewer for years without problems on both computers.  In the past few days I used ALIEN1 to remotely connect to my uncle’s laptop (located in another city) and helped him resolve some issues.  TeamViewer had no problems.

ALIEN2 was out of service for a few months (repairs) but is now back in service.


When I’m on ALIEN2 TeamViewer indicates ALIEN2 and ALIEN1 are offline when both machines are actually running and with TeamViewer running.  Same thing when I’m on ALIEN1.  Both machines are in the same house on the same network, connected by ethernet.  Yet at the same time, TeamViewer on both machines can see my brother’s laptop online and my accountant’s laptop online.  Both are in different cities.

I never ran into this problem before.

I'd appreciate suggestions or ideas.