CQM - I think you are a bit confused.
Sounds like you are using a laptop and connecting over wifi to a home router - probably attached to FiOS (since you mention fiber).
Go here:
www.ipchicken.com and replace the last number with a 1.
Then ping it by opening up a command prompt (windows start button + R on the keyboard) and type "ping xxx.xxx.xxx.1" where xxx = the IP address you saw on ipchicken.
Report that number back. I expect you'll be in the 20-30ms range.
Next, if you have the option to use SMART order routing I assume you are using a retail broker or prop firm's software - probably a retail broker with the option to route orders directly to an exchange vs. true DMA. I don't want to sound like a jerk but if you really had DMA you probably wouldn't be asking why you aren't getting fills.
I don't know why you are allowed to send sub-penny orders. Your broker/trading platform may allow this but have you checked to see if the ECN you are routing to supports sub-penny orders? (It probably does not.) You should read the fine-print of your broker's contract. Often times if you send non-marketable orders (like a sub-penny order to an exchange that doesn't allow sub-penny orders) your broker reserves the right to internalize OR not accept that order - so you may think you are being slick but you are actually getting screwed over by your broker.
Also, you have to watch out trying to provide liquidity AND sending orders at or over the NBBO - if you do that you may get dinged for taking not adding.
Quote from cqm:I am using DMA, and I suspect my inability to get filled has to do with broker internalizers.
If your broker internalizes orders this is not DMA - even if you specify a route you do not have Direct Market Access - your orders are piped through several risk checks and there will be (what is considered by today's standards) extremely high latency and delays for your order to get from your broker through to the ECN you specify.
15ms is a really long time and hard wired is always preferred over wireless. I would make sure you have a wired connection and then also check your modem/router connections and capacity. For example, most Linksys home/retail routers can't handle much over 20-25mb/sec sustained. If you want to keep using a home/retail type router I'd suggest using QoS and network prioritization to make sure your machine gets first dibs on the bandwidth.
The reason why you aren't getting filled is because you are getting picked off or held up. Either the price has moved by the time your order gets to the exchange or your broker is holding up your order and using it as an exit.