Quite the opposite. I had flakey connections with my ADSL modem last summer and I traced this down to exactly what you found. That darn telephone cable. Replaced it. Last fall, things got really odd. When the room was cool, the connection was good. As it warmed up, the connection with the model was bad and inconsistent. I traced this back to the cable again. I got tired of this. Moved the ADSL modem right where the telephone cable enters the home. Directly soldered on a jack to the telephone company wire and then into the modem. Thereafter, the whole house is CAT5. All problems gone. I even gained speed with less overhead taking care of transmission errors, etc. Solder, there is no substitute. I've been soldering electronics since the 70s.