I have an S9 that I have been trying to connect to various pools, unsuccessfully.

It seems that any pool with port 3,xxx will not connect. For example,
stratum+tcp://stratum.antpool.com:3333
stratum+tcp://sha256.usa.nicehash.com:3334
stratum+tcp://sha256.eu.nicehash.com:3334
stratum+tcp://us-east.stratum.slushpool.com:3333

All do not work and show as dead.

However,
stratum+tcp://stratum.antpool.com:443
stratum+tcp://stratum.antpool.com:25

Both work fine.

I have 10x D3 and 10x L3+ miners arriving and I want to mine on Nicehash, but am worried that I won't be able to connect to the stratum pool when they arrive.

1. I have updated to the newest Bitmain S9 firmware.
2. I have forwarded port 3334 on my router.
3. I have disabled IPv6.

Using a Windows computer on the same network, I do get a ping response when I type in:
ping -n 50 -l 128 speedtest.usa.nicehash.com

But I don't get a ping response on:
ping -n 50 -l 128 speedtest.usa.nicehash.com:3334

Any other thoughts would be very helpful!