I haven't changed any configuration, merely upgraded bitcoind.

Working: the following scenario where machine 'A' has the ASIC, and bfgminer, and machine 'B' is running bitcoind-0.17 on testnet:

machine 'A' (bfgminer, w/ ASIC):

$ sudo bfgminer -o http://192.168.1.2<machine B's IP>:18332 -u test -p test --coinbase-address 2Mttvmg6ZeCr8eLNCNiLnHqcnhbkSKinZYE

machine 'B' (bitcoind-0.17.0 - full node, running testnet):

$ bitcoind -conf=/home//.bitcoin/bitcoin-core-testnet.conf

where -conf=/home//.bitcoin/bitcoin-core-testnet.conf contains:

daemon=1
dbcache=14096
datadir=</path/to/non-default data dir>
debug=1
testnet=1
server=1
rest=1
</path/to/non-default wallet name>.dat
mintxfee=0.0000001
walletrbf=0
upgradewallet=0
walletbroadcast=0
flushwallet=0
privdb=0
[test]
rpcuser=test
rpcpassword=test
rpcbind=<machine B's IP>192.168.1.2
rpcbind=127.0.0.1
rpcport=18332
rpcallowip=127.0.0.1
rpcallowip=<machine A's IP>192.168.1.1

• however - NOT Working: the following scenario where machine 'A' has the ASIC, and bfgminer, AND is running bitcoind-0.18 on testnet, results in (bfgminer logfile) errors:

[2019-05-23 12:11:23] setrlimit: Soft fd limit not being changed from 1024 (FD_SETSIZE=1024; hard limit=1048576) [2019-05-23 12:11:23] Started bfgminer 5.5.0 [2019-05-23 12:11:24] minergate: /tmp/connection_pipe: Cannot connect [2019-05-23 12:11:24] minergate: /tmp/connection_pipe_sp30: Cannot connect [2019-05-23 12:11:24] add_local_gbt: Did not find rpcpassword in /etc/bitcoin/bitcoin.conf [2019-05-23 12:11:24] Probing for an alive pool [2019-05-23 12:11:24] Testing pool http://192.168.1.1:18332 [2019-05-23 12:11:24] HTTP request failed: The requested URL returned error: 500 Internal Server Error [2019-05-23 12:11:24] Failed to connect in json_rpc_call [2019-05-23 12:11:24] HTTP request failed: The requested URL returned error: 404 Not Found [2019-05-23 12:11:24] Failed to connect in json_rpc_call [2019-05-23 12:11:24] initiate_stratum with sockbuf=(nil) [2019-05-23 12:11:24] Stratum connect failed with TLS to pool 0: gnutls_handshake() failed: An unexpected TLS packet was received. [2019-05-23 12:11:24] JSON decode failed(1): '[' or '{' expected near 'HTTP' [2019-05-23 12:11:24] Failed to resume stratum, trying afresh [2019-05-23 12:11:24] initiate_stratum with sockbuf=0x7f232001dc40 [2019-05-23 12:11:25] Stratum connect failed with TLS to pool 0: gnutls_handshake() failed: An unexpected TLS packet was received. [2019-05-23 12:11:25] JSON decode failed(1): '[' or '{' expected near 'HTTP' [2019-05-23 12:11:25] Initiate stratum failed [2019-05-23 12:11:25] Closing socket for stratum pool 0 [2019-05-23 12:11:25] FAILED to retrieve work from pool 0 http://192.168.1.1:18332 [2019-05-23 12:11:25] Pool 0 slow/down or URL or credentials invalid [2019-05-23 12:11:25] No servers were found that could be used to get work from. [2019-05-23 12:11:25] Please check the details from the list below of the servers you have input [2019-05-23 12:11:25] Most likely you have input the wrong URL, forgotten to add a port, or have not set up workers [2019-05-23 12:11:25] Pool: 0 URL: http://192.168.1.1:18332 User: test Password: test No servers could be used! Exiting.

and where the bitcoind log merely indicates:

2019-05-24T20:57:04Z Received a POST request for / from 128.120.193.169:33400 2019-05-24T20:57:04Z ThreadRPCServer method=getblocktemplate user=test 2019-05-24T20:57:04Z Received a POST request for / from 128.120.193.169:33402 2019-05-24T20:57:04Z ThreadRPCServer method=getwork user=test