DSL flaky … is it the Powerbook 1400 … or not?

The DSL at home was a little tenuous over the weekend (it’s DSL Extreme delivered over SBC/AT&T lines). I thought it was the Powerbook 1400 fritzing out, but then the signal looked good on the modem but wouldn’t come through on the iBook G4. Later it worked on both, but the next day, I couldn’t get the DSL modem to work with the Powerbook 1400 (Global Village PowerPort Platinum PC Card with 28.8K modem and 10-BaseT Ethernet).

I wonder, is it my setup, or does the signal level out of the modem vary? Would it help if I had a router connected between the modem and the PB 1400 (at least then I could see if they were connecting from an Ethernet standpoint). I’ve also had seamless connections through my AirLink 101 5-port switch ($7 at Fry’s — buy two, they’re small). I’d have to run these tests at home to see what’s really going on.