問題還是不定時發生, 懶得以Packetyzer 抓原因, 先更換Modem, 再調整TOS, 因為在設定AR4031C QoS 時, 發現好像不能使用某些TOS 數值 (IP Precedence), 而SPA1001 實際上預設數值 (SIP:0x68/AF31, RTP:0xb8/EF) 是針對DiffServ, 不是TOS, 所以先分別改成SIP:0, RTP:0x48, 再繼續觀察, 不過小弟於AR4031C QoS 有設定IP Precedence:2, IP Type of Service: Maximize Throughput, 所以事實上TOS=0x48, 應該會蓋過SPA1001 的設定值

IP QoS的流分類方法詳解 - Net130.com (http://www.net130.com/CMS/Pub/Tech/tech_zh/2007_11_18_25871.htm)
Quality of Service, diff serv code point, ip precedence (http://www.rhyshaden.com/qos.htm)