UPS or voltage stabilizer?

Question

Uninterruptable power source

There is a TL-WDR3600 router with OpenWrt CC 15.05.1 on board. Messages periodically jump in the log, and the port can be 3 or 4 which is free.
[ 350.024000] Atheros AR8216/AR8236/AR8316 ag71xx-mdio.0:00: Port 3 is up
[16700.128000] Atheros AR8216/AR8236/AR8316 ag71xx-mdio.0:00: Port 3 is down
[26204.2000082] Atheros66 AR8316 ag71xx-mdio.0:00: Port 4 is up
[38910.284000] Atheros AR8216/AR8236/AR8316 ag71xx-mdio.0:00: Port 4 is down
Googled on this topic and they say that the problem is with increased voltage on the cable or network . What makes sense to put UPS or voltage stabilizer?
PS: The provider's support pointed out twice the increased resistance on the cable.

Answer 1

problem with increased voltage on the cable or network.

On what cable? On what network? In computer or power 220V?
Again, what cable? Ethernet cable from your ISP? Cables from 3 and 4 ports? Then look / change these cables, re-crimp the connectors, change to solid ones if there are twists.
Neither a stabilizer nor an uninterruptible power supply will not help.

Answer 2

check the conduits on the router's power supply.