SAN DIEGO, Aug. 28, 2026 /PRNewswire/ -- Robbins Geller Rudman & Dowd LLP announces that purchasers of Cogent Communications Holdings, Inc. (NASDAQ: CCOI) common stock between February 29, 2024 and May 1, 2026 (the "Class Period"), have until Monday, September 21, 2026 to seek appointment...