2014-01-23, 02:16
I'm feeling like an idiot, but i think the router is really the problem here.
My router (Fritz!Box 6360) has an "energy saving" option for the 4 LAN ports. You can manually set the speed of the port to 1 Gbit/s or 100 Mbit/s (to save energy, esp. if you only have a 100 Mbit/s device).
Obviously i had set the LAN port for my iMac to 1 Gbit/s. Due to the fact, that i don't have another 1 Gbit device, i couldn't test it so far. But back to topic: During further iperf tests between my iMac and my notebook i noticed that the iMac could download easily 90 Mbit/s from the notebook, but could only send 10-20 Mbit/s. After ruling out a software problem, i thought that the LAN port of my iMac must be damaged.
Well i don't know really why, but i played later a little bit with several options router and set all LAN ports to 100 Mbit/s and BOOM - speeds up to 90-95 Mbit/s!?! I changed it back to 1 Gbit/s and all the movies were stuttering again and i could reproduce the long mentioned speed problems. Changed it back again to 100 Mbit/s - everything worked fine again with 90-95 Mbit/s.
In summary: The 1 Gbit/s mode is f**ing everything up and this mess cost me 5 evenings. On the other hand: The Pi is flying again :-) I will exchange my router and will report if there is an improvement.
Thank you both for your help and patience!
My router (Fritz!Box 6360) has an "energy saving" option for the 4 LAN ports. You can manually set the speed of the port to 1 Gbit/s or 100 Mbit/s (to save energy, esp. if you only have a 100 Mbit/s device).
Obviously i had set the LAN port for my iMac to 1 Gbit/s. Due to the fact, that i don't have another 1 Gbit device, i couldn't test it so far. But back to topic: During further iperf tests between my iMac and my notebook i noticed that the iMac could download easily 90 Mbit/s from the notebook, but could only send 10-20 Mbit/s. After ruling out a software problem, i thought that the LAN port of my iMac must be damaged.
Well i don't know really why, but i played later a little bit with several options router and set all LAN ports to 100 Mbit/s and BOOM - speeds up to 90-95 Mbit/s!?! I changed it back to 1 Gbit/s and all the movies were stuttering again and i could reproduce the long mentioned speed problems. Changed it back again to 100 Mbit/s - everything worked fine again with 90-95 Mbit/s.
In summary: The 1 Gbit/s mode is f**ing everything up and this mess cost me 5 evenings. On the other hand: The Pi is flying again :-) I will exchange my router and will report if there is an improvement.
Thank you both for your help and patience!