Possible culprit: degradation of compound between cpu and metal lid
Possible culprit: degregation of power regulation to network ic due to prolonged heat exposure, causing network instability over time.
Attempted first solution: clean black compound with isopropyl alcohol on arm ic and top of lid dip that contacts it. Take 15mmx15mmx0.8mm copper plate, get arctic silver on both sides. Put between cpu and plate contact.
Result: lost stability sooner. Heat is probably going around to network section of board faster. Thermal compound meant to balance heat load between board and lid?
Attempted second solution: keep first solution in place and... At least it works?