Sophos XG slow down Internet bandwidth

Hi,

I'm currently having Internet bandwidth issues when my network traffic goes through Sophos XG firewall. My ISP is supposed to be mbps 940up/940down, but I got only 100/100 mbps per device, some devices losing Internet connection sometimes here and there when a heavy bandwidth task occurs on the network

Here's my config : 

• Sophos XG - SFOS 19.5.2 MR-2-Build624
• IPS Protection ON
• WAN PPPoE without VLAN
• WAN Link Mode : 1000 Mbps Full-Duplex
• Auto-negociation for media type ON
• Forward Error Correction (FEC) OFF
• MTU : 1492
• MSS : automatic 1444
• DoS settings : 

• Trafic shaping : 
  No rules and policies is supposed to use any traffic shaping rules to me knowledge

• Firewall and NAT rules : 

I already tried these troubleshoot steps, without success : https://support.sophos.com/support/s/article/KB-000038912

Also tried to bypass Sophos XG and the Speed Tests were up to my ISP speeds

Is there anything else I can do to trouble shoot and bring back those speeds to normal?

Thanks in advance and regards