Slow performance behind firewall

Question

Hi, I purchased a used XG 115 Rev. 2 firewall and installed Sophos Home Edition so I can use it as a perimeter firewall at home. My internet connectivity is FTTH 1 Gbps/300 Mbps. If I connect directly to the ISP router by running a speed test I get 900 Mbps/280 Mbps. If I connect behind the firewall, while disabling any firewall controls (DPI, IPS, AV, etc...) I can never get more than 550/250 Mbps. Why? I also replaced the 4GB RAM bank with an 8GB bank (even though I know the Home Edition limitation is 6GB). What else can I do to be able to use this firewall satisfactorily? During the tests, only my PC was connected to the firewall's LAN, If I connect the entire home data network I think that the performance will be even lower... 
 Thanks! 
 Bye

rfcat_vk · Answer

Hi, 
 you appear to have hit the performance limit of the xg115. My Rev3 does slightly better on the 1000/50 fttp link with around 600-650 using my current configuration. The number of users should not have any significant affect on throughput. 
 Ian