I have two V6 boxes but they do not recognise each other so I can not watch programmes recorded on one on the other.It says there may be a problem with network connection but the check says they are individually OK.
Try,on both Tivos
HELP-SETTINGS-DEVICES-NETWORK REMOTE CONTROL-ALLOW NETWORK REMOTE CONTROL
This has worked for a number of people.
If it doesn't work for you, I don't recall any other solutions