I am having download speed issues as well. I pay for 1100/200 Mbps and I'm only getting 150/??.
Set-up: Xfinity XB7-T with R3 (.41) in DMZ. PS5 to R3, wired and in DMZ.
Will start speedtest on both R3 and PS5. On R3 the speed rolls to 200Mbps then throttles to 150 and persists thereafter. Same while monitoring network traffic while downloading file on PS5.
I disabled Smartboost and same results.
I disabled Smartboost and Ping Optimizer/Steady Ping and the PS5 os speedtest showed 830Mbps and 11.5 Better, but that upload is not great.
Any suggestions?