@MrParticular 

I think you could use the Iperf tool to test the speed of the router, just elimiate the influence by other element first.

If the speed is around 600Mbps, it may be caused by the ISP network. We can try

1. Bypass the R600VPN, verify the speed from the ISP modem with the same cable is as expected.

2. A hard reset on the router may help sometimes, then reconfigure the router.

3. Try MAC Clone: after you connect the PC to the ISP modem for test, connect the same PC to the router and select Clone current PC's MAC under >>Network--MAC<<.

Good Luck!

The NAT throughput of TL-R600VPN V4 is 680Mbps.

I did a performance test of the TL-R600VPN.  I connected a MacBook Pro directly to the cable modem, and measured (with "Wifi Speed Test v 1.5.7) ~860Mbps download speeds; it was fairly consistent (less than 5% variation over a few minutes).

I then put the TL-R600VPN between the cable modem & a Gigabit switch; in that situation, the measured download speed was consistently ~560Mbps.  That is somewhat consistent with the router's limitation noted above.  (The CPU usage graph on the status page of the R600 also showed near 100% usage.)

FYI: Besides the NAT translation speed limitation noted in my previous note, I found another limitation of the TL-R600VPN:  The maximum number of IP addresss reservations in the DHCP server is 80!  (Which means there's no benefit in setting up a reserved size larger than 80, too.)

FYI-2: I have replaced the TL-R600VPN with a Ubiquity EdgeRouter 4.  It allows more than 80 reserved (static) address reservations.  More importantly, the measured throughput to my ISP jumped from the ~mid-600's Mbps to the mid-800 Mbps ... which is the limitation of the speed of the modem (and what I'm paying for).  And the EdgeRouter 4 is not at all close to being CPU-saturated at that level, either.  So, it you are paying for an ISP connection over 600 Mbps, you may want to replace a TL-R600VPN with something faster.  (The EdgeRouter does have a "Wizard" to configure Dual-Wan ... with or without failover; just don't use the "Default" configuration Wizard. p.s.: do any firmware update before choosing a configuration Wizard.)

@Dan_C. 

Hey Dan, I am the OP and I also switched to a Ubiquity EdgeRouter 4 shortly after I posted how slow I found the TL-R600VPN to be (and before the return window closed). While the ER4 was slightly more difficult to set up (particularly choosing which version of their firmware worked best) I am getting the full downlaod speed my modem can supply. I guess I have been using it over a year now and have no complaints, I even set it up with a transition script so I am notified of failovers, which was something else the tp-link did not offer.

Dave

  @MrParticular 

Hi!!!

I have Internet Service Provider WAN1 (100MB) and WAN2(50MB) respectively and i configured port 5 (LAN) as a LAN and connect Unifi AC-LR AP.

But when i speedtest on standalone system on LAN port i got 150+ MB internet speed but on WiFi it shows just 50MB.

So kindly guide me is there is a configuration issue i did in TPLINK ER605 b/c in LAN the speed is upto the mark but on Wifi it is not.

I appreciate your response.

Thanks.