Thanks. I was playing wth all these ports all these while.I can't remember the logic behind my QOS priority settings. But you might want to try different permutations.
Since Router -> Port 7 of SG2008, maybe on SG2008, you can set priority for Port 7 to highest?
Basically play around with the QOS priorities on Port 7 & 8 on SG2008, and Port 4 and5 on SG105E
One question, priority set to highest is only to the access port (i.e port 4 of SG105E and port 7 of SG2008) or both port 4&5 and 7&8? -- hope you can remember.
I did a strip down test earlier, direct connection from STB to Asus, works. Then STB to SG105E to Asus, works. All these tests were done after total shutdown for 15 mins to ensure that the sessions are reset.
This might narrow down my investigation on what went wrong.