Why does my computer keep switching lan

[jopayne]

Hello,
My dads pc keeps trying to switch from LAN2 to LAN5 and losing connection.His router is fine and been told the problem lies in the pc.He's in his 60's and needs help i can't give him! Its running on vista. Are there some settings he should change?????

 

[GhislainG]

Does his PC have 2 LAN controllers? If you need help, please provide info about the system and the LAN connections.