This scenario sounds a lot like what I went through a few days ago. Even though you mention a static IP, I suspect a dynamic IP instead. I'm only guessing here because I don't have enough info to say for sure if the IP is static or not.
But, here's what happened to me and my A3. The entire machine went berserk throwing X's all over the hashing boards. I unplugged it and eventually did a hard reset. I mistakenly thought it would preserve the IP address. But, I would not connect to the miner's web interface. What drove me nuts was the fact the miner was continuing to mine and I could ping what I thought was the IP address. I eventually turned to my main router connected to my cable modem and had a look at the DHCP Routing Table. Sure enough, the A3 IP address had swapped places with my ROKU box in the living room. I had been pinging and trying to connect to my ROKU. Ouch. Lesson learned.
I thought I might post an update. I just now switched back to the Siamining pool from Antpool. I let Antpool run for minutes shy of 24 hours on and I believe I made maybe 100 SC less. The A3 has been running for 10 minutes with both fans and temps in the nominal range. No crazy hashing board X's and only 2 HW errors so far. Fingers crossed.
I just want to light the point 1 suggested by reinisp 29 days ago.
We have to keep in mind that the number of SC mined is pretty much the same between two close dates because the difficulty grows up according to the hashrate even if the hashrate explode.
Before A3 the total hash rate was about 500 TH/s so one good GPU did 2 GH/s for 150 Watts (https://sia.today/9/best-amd-gpus-hashrate) so there were about 500000/2 = 250000 GPU which mined Siacoin.
The total power consumption was about 250000 GPU x 150 W = 37.5 MegaWatts
When the A3 arrived, we can think that all GPU stopped mining immediately. The high electrical consumption didsn’t allow to earn some money against A3 (75watts/GH/s versus 1.6 Watts/GH/s and GPU had to mine much more time to mine 1 SC because of the difficulty increasing).
The Hashrate when A3 arrived went to about 11900 TH/s. One A3 use about 1275 Watts for mining about 815 GH/s so we can estimate there were about 11900TH/s / 0.815 = 14602 A3. So the total consumption was about 14602 A3 x 1275 W = 18.6 MegaWatts.
Right now the total hash rate is about 24000 TH/s so there are about 24000 TH/s / 0.815 TH/s = 29447 A3 and the total consumption is right now about 29447 A3 x 1275 Watts = 37.5 MegaWatts
As we can see, the A3 owners do not need to convert more SC than the GPU owners before A3 comes.
So the point 1 is not true and the electrical consumption doesn’t impact right now the price of SC.
Siamining.com I find to be the best option for the A3... since the second batch shipped the diff has doubled and I am making about half of what I was. I look for other pools to use for all of my Bitmain equipment. I don't like using antpool as I'd rather not give any extra money to bitmain after they flooded the market and screwed us all.