Currently I have experienced collisions and packet loss on an outer routing switch (1-2% from the States and above 6% when tested from Europe). In a basic way infrastructure looks like
Where outer switch is Netgear DS524 (previously some Linksys). NSA TS and NSA HA are Sonciwall 2400 family. Internet test gateway and WiFi are network devices before a firewall (a PC and a wireless guest AP).
I have tested if there are packet loss on VLANs behind a firewall but all work as should.
What can cause those packet loss on that outer switch? Any good suggestions for a hardware replacement (up to 8 ports, rack mountable)?