I'm trying to configure a rpi to monitor the wlan and wired connections. both are on the same network (192.168.1.0/24). when both are enabled, I'm having a hard time using the wireless connection. For example, when I curl --interface enu1u1u1 http://2.18.244.76, tcpdump as expected goes:

17:27:41.606428 enu1u1u1 Out IP 192.168.1.101.45516 > 2.18.244.76.80: Flags [S], seq 3074758675, win 64240, options [mss 1460,sackOK,TS val 1422732498 ecr 0,nop,wscale 7], length 0
17:27:41.611238 enu1u1u1 In  IP 2.18.244.76.80 > 192.168.1.101.45516: Flags [S.], seq 69448321, ack 3074758676, win 65160, options [mss 1452,sackOK,TS val 527341513 ecr 1422732498,nop,wscale 7], length 0
17:27:41.611400 enu1u1u1 Out IP 192.168.1.101.45516 > 2.18.244.76.80: Flags [.], ack 1, win 502, options [nop,nop,TS val 1422732503 ecr 527341513], length 0
17:27:41.611657 enu1u1u1 Out IP 192.168.1.101.45516 > 2.18.244.76.80: Flags [P.], seq 1:76, ack 1, win 502, options [nop,nop,TS val 1422732503 ecr 527341513], length 75: HTTP: GET / HTTP/1.1
17:27:41.616315 enu1u1u1 In  IP 2.18.244.76.80 > 192.168.1.101.45516: Flags [.], ack 76, win 509, options [nop,nop,TS val 527341518 ecr 1422732503], length 0
17:27:41.632673 enu1u1u1 In  IP 2.18.244.76.80 > 192.168.1.101.45516: Flags [FP.], seq 1:517, ack 76, win 509, options [nop,nop,TS val 527341518 ecr 1422732503], length 516: HTTP: HTTP/1.0 400 Bad Request
17:27:41.633322 enu1u1u1 Out IP 192.168.1.101.45516 > 2.18.244.76.80: Flags [F.], seq 76, ack 518, win 501, options [nop,nop,TS val 1422732524 ecr 527341518], length 0