You know this would be a hell of a lot less painful if you provided details.
- Defective POTS
- Faulty port at exchange
- Defective other device on the line (Fax, alarm sys etc)
- Overheating router
- Leaking microwave nearby
- Rusted connectors
- Moisture in cable/connectors
- Poor line stats. Sometimes they randomly change.
- ISP
Start with 4 & 8, then 1 and 3. Netgears get hot. Mount it vertically & see if it changes anything. If you think its the ISP then buy some cap from a different ISP & see. Rather unlikely though if you had the problem under Afrihost and MWeb.