client stopped getting backed up after June 18

I have the following strange problem with a FreeBSD amanda server
running 2.5.1p3 and a Fedora 7 Linux client running the same. The last
successful backup of the client was on June 18. Ever since then, the
backup report has shown:

FAILURE AND STRANGE DUMP SUMMARY:
  jupiter  mapper/VolGroup00-LogVol00  RESULTS MISSING
  jupiter  sda1                        RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol02  RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol05  RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol06  RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol07  RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol08  RESULTS MISSING
  jupiter  mapper/VolGroup00-LogVol09  RESULTS MISSING
  planner: ERROR Request to jupiter failed: timeout waiting for ACK

I can't find any useful information on the client except for .debug
files in /var/log/amanda/amandad that end with:

amandad: time 0.000: dgram_recv(dgram=0x39e6e2e928, timeout=0,
fromaddr=0x39e6e3
e920)
amandad: time 0.000: (sockaddr_in *)0x39e6e3e920 = { 10, 566, 0.0.0.0 }
amandad: time 9.122: dgram_recv(dgram=0x39e6e2e928, timeout=0,
fromaddr=0x39e6e3
e920)
amandad: time 9.122: (sockaddr_in *)0x39e6e3e920 = { 10, 566, 0.0.0.0 }
amandad: time 19.816: dgram_recv(dgram=0x39e6e2e928, timeout=0,
fromaddr=0x39e6e
3e920)
amandad: time 19.816: (sockaddr_in *)0x39e6e3e920 = { 10, 566, 0.0.0.0 }
amandad: time 29.814: pid 9520 finish time Fri Jun 29 00:44:59 2007

Doesn't tell me much. Any idea where I could start looking?

- Julian