TNS:listener times out every 2 hours on VPN

Question

I have a locally installed Oracle XE instance I use, but it times out every 2 hours on our corporate VPN. It's like clockwork, 2 hours after connecting I get:

ORA-12514, TNS:listener does not currently know of service requested in connect descriptor

If I reconnect the VPN it starts working again, 2 more hours then reconnect. Any way to avoid this? Any way even to refresh it without reconnecting the VPN, as that in itself is a total pain.

Update

listener.ora looks like:

DEFAULT_SERVICE_LISTENER = XE

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\Oracle\dbhomeXE)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:C:\Oracle\dbhomeXE\bin\oraclr.dll")
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = <FQDN>)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )

Where is the fully qualified domain name of my machine.