With age, my Zyxel 660-HW started to be instable on all 4 LAN
connections. All other functions were fine.
Symptoms we poor LAN performances and all LAN connections lost and
soon reestablished every 15 seconds or so.
The problem has been fixed replacing one electrolytic capacitor. Some
detail at:
http://xoomer.alice.it/egirland/zyxe...r%20brief.html

As all the other caps measured bad ESR value, should your Prestige
expose strange behaviors, I suggest you to replace all of them.
Emanuele.

writes:

With age, my Zyxel 660-HW started to be instable on all 4 LAN
connections. All other functions were fine.
Symptoms we poor LAN performances and all LAN connections lost and
soon reestablished every 15 seconds or so.
The problem has been fixed replacing one electrolytic capacitor. Some
detail at:
http://xoomer.alice.it/egirland/zyxe...r%20brief.html

As all the other caps measured bad ESR value, should your Prestige
expose strange behaviors, I suggest you to replace all of them.
Emanuele.

Wow, thanks for that!

I have an old 660HW-61 where the switch (LAN) part started acting
weird. As it was out of warranty I bought another one.

I just checked the same cap, 220µF 10V, and got an ESR reading of 1.1
ohm, which is high. The other 220µF cap just besides it reads 0.14
ohms, which should be fine.

The other two caps you indicate are also marginal, 0.65 ohms, while
all others are around 0.15 ohms.

Now I just need to get some new caps. :-)

Thomas