The cause of the reduced Internet speed was an old switch

The connection to the Internet is via my cable modem ch7466ce from compal (In bridge mode), the router TL-WDR4300 from tp-link and then finally via the switch from netgear model gs108 (Construction year 2003).
My Internet provider is Vodafone with 400 Mbps downlink and 25 Mbps uplink. But unfortunately I do not have the full speed on the computer. As it turned out, the old netgear switch was the cause.

Cable Modem ch7466ce from compal:

Technical description:

  • Router with integrated EuroDOCSIS 3.0 modem for Internet on the cable connection.
  • Telephone connection (RJ11) on the cable modem + TAE-NFN adapter
  • Dual WLAN AC + N with 1.300 (5 GHz) + 450 Mbit / s (2.4 GHz) simultaneously
  • 4x Gigabit LAN for PC, game console and more
  • USB port for USB storage media
  • Integrated firewall, protection against denial-of-service (DoS) attacks and network address translation (NAT)
  • Integrated DHCP server.
  • Easy setup via the browser interface

Router TL-WDR4300 (N750 Wireless Dual Band Gigabit Router ) from tp-link:

Technical description:

  • Simultaneous 2.4GHz 300Mbps and 5GHz 450Mbps connections for 750Mbps of total available bandwidth
  • 2*USB Ports – Easily share a printer locally and files & media with networked devices or remotely via FTP server
  • Full gigabit ports ensure ultimate transfer speeds
  • Achieves blazing WAN to LAN throughput of over 800Mbps with hardware NAT
  • Guest Network Access provides secure Wi-Fi access for guests sharing your home or office network*
  • Construction year 2012
  • Link

Switch gs108 from Netgear:

Technical description:

  • Network Connections: 8x RJ-45
  • Speeds: 8x RJ-45 (10/100 / 1000Base-T)
  • Backplane: 16Gb/s, 11.58Mp/s, 9KB jumbo frames, 192kB packet buffer , 8k Mac addresses
  • Supported features: 802.1, 802.1p, 802.3, 802.3AZ, 802.3ab, 802.3az, 802.3x
  • Construction year 2003
  • Link

Speedtest:

I used speedtest.net which has very good results for high speed internet connections:

As you see I got 280 Mbps download speed only.

I replaced the old switch with a newer one:

Switch sg110d-08 from Cisco:

Technical description:

  • Network connections: 8x RJ-45
  • Speeds: 8x RJ-45 (10/100 / 1000Base-T)
  • Backplane: 16Gb/s, 11.9Mp/s, 9KB jumbo frames
  • Supported features : 802.1p, 802.3, 802.3ab, 802.3az, 802.3u, 802.3x
  • Construction year 2015
  • Link

Speedtest:

Now I got full speed.