This is the most bizarre issue. I have worked with small to mid size networks for quite a long time and can say I'm comfortable connecting hardware. Where you will start to lose me is with managed switches and firewalls.

To start, let me describe my network (sigh, shouldn't but I MUST solve this).

1) Comcast Cable Internet
2) Motorola SURFboard eXtreme Cable Modem.
    a) Model: SB6120
    b) DOCSIS 3.0 and 2.0 support
    c) IPv4 and IPv6 support
3-A) Cisco Small Business RV220W Wireless N Firewall
    a) Latest firmware
    b) Model: RV220W-A-K9-NA
    c) WAN Port to Modem (2)
    d) vlan 1: work
    e) vlan 2: everything else. 
3-B) D-Link DIR-615 Draft 802.11 N Wireless Router
    a) Latest firmware
    b) WAN Port to Modem (2)
4) Servers connected directly to firewall
    a) If firewall 3-A, then vlan 1
    b) CAT5e patch cables
    c) Dell PowerEdge 1400SC w/ 10/100 integrated NIC (Domain Controller, DNS, former DHCP)
    d) Dell PowerEdge 400SC w/ 10/100/1000 integrated NIC (VMWare Server)
4) Linksys EZXS88W unmanaged Workgroup 10/100 Switch 
    a) If firewall 3-A, then vlan 2
    b) 25' CAT5e patch cable to firewall (3-A or 3-B)
    c) Connects xBox 360, Blu-Ray player, PC at TV
5) Office equipment connected directly to firewall
    a) If firewall 3-A, then vlan 1
    b) ~80' CAT6 or CAT5e patch cable to firewall (3-A or 3-B)
    c) Connects
        1) Dell Latitude laptop 10/100/1000
        2) Dell Inspiron laptop 10/100
        3) Dell Workstation 10/100/1000 (Pristine host, VMWare Workstation 7.x with many bridged VM's)
        4) Brother Laser Printer 10/100
        5) Epson All-In-One Workforce 310 10/100
5-A) NetGear FS116 unmanaged 10/100 switch
    a) I've had this switch for a long time and never had issues.
5-B) NetGear GS108 unmanaged 10/100/1000 switch
    a) Bought new for this issue and returned.
5-C) Linksys SE2500 unmanaged 10/100/1000 switch
    a) Bought new for this issue and returned.
5-D) TP-Link TL-SG10008D unmanaged 10/100/1000
    a) Bought new for this issue and still have.
6) VLan 1 Wireless Connections (on same subnet if 3-B)
    a) Any of those at 5c
    b) HP Laptop
7) VLan 2 Wireless Connection (on same subnet if 3-B)
    a) IPad, IPod
    b) Compaq Laptop
    c) Epson Wireless Printer

Shew, without hosting a diagram I hope that paints a good picture.

The Issue The breakdown here is at item 5. No matter what I do I cannot have a switch at 5 and have to run everything wireless regardless of router.

Issues related to using a switch (point 5 above)

• SpeedTest is good.
• Poor throughput to other devices if can communicate at all.
• Usually cannot ping other devices even on the same switch although, when able, ping times are good.
• Eventual lose of connectivity and can "sometimes" be restored by unplugging everything for several days, not minutes or hours but we're talking a week if at all.
• Directly connect to computer gives good internet connection however throughput to other devices connected to firewall is at best horrible. Yet printing doesn't seem to be an issue as long as they are connected via wireless.
• I have to force the RV220W to 1000Mb on the respective port if using a Gig Switch

Issues related to using wireless in place of a switch (point 5 above)

• Poor throughput to other devices if can communicate.
• SpeedTest is good.

Bottom line

• Internet speeds are awesome. By the way, Comcast went WAY above and beyond to make sure it was not them. They rewired EVERYTHING which did solve internet drops.
• Computer to computer connections are garbage
• Cannot get switch at 5 to work, yet other at 4 has never had an issue. Direct connection, bypass switch, is good for DHCP and internet.
• DNS must be on server, not firewall.

Cisco insists its my switches but as you can see I have used four and two different cables with the same result. My gut feeling is something is happening with routing. But I'm not smart enough to know that answer.

I run a lot of VM's at 5-c-3, could that cause it?

What's different compared to my previous house is I have introduced Gigabit hardware (firewall/switches/computers).

Some of my computers might have IPv6 turned on if I haven't turned it off already.

I'm truly at a loss and hope anyone has some crazy idea how to solve this. Bottom line, I need a switch in my office behind the firewall. I've changed everything. The real crux is I will find a working solution and, again, after days it will stop working. So this means I cannot isolate if its a computer since I have to use them. Oh and a solution is not throwing more money at this. I'm well into $1k already. Yah, lame.