I heard this question come up a couple of times this week, the latest today: "I have a router on my home network: will it be affected by this Daylight Saving Time change?"
And "What about PBX phone systems?"
Generally speaking, no.
For the most part, I learned (thanks, Bob) that most telecom equipment does not utilize the system clock from the computer and, in businesses and enterprises, is updated manually during every DST change. This will allow the date/time on a desktop phone to be displayed correctly. For international voice traffic synchronization, you'll often find that telephony equipment matches to a cesium clock that is maintained by the US government in Colorado. These systems use a standard time -- Coordinated Universal Time (aka UTC) -- so there shouldn’t be any issue there.
Also, Bob noted that "the vast majority of Network Equipment (>95%) uses GMT so is unaffected by the DST time change."
I'll add that many popular routers utilize NTP using Coordinated Universal Time (UTC) and is usually not impacted by individual time zone changes. Some routers may be configured to specific time zones, so it is best to check the documentation that comes with your system. For more info, also see Cisco's NTP info page, with more than you will probably ever care to know about the subject. 😉