I'm seeing many errors like this in my logs. I can post more but this is a small snippet. I have a gt-ac5300 router running firmware 3.0.0.4.384.81686
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.255.6.34 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=47 ID=36497 DF PROTO=UDP SPT=53049 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.16.76.130 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=51 ID=3302 DF PROTO=UDP SPT=26457 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=50.7.114.59 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=53 ID=60346 DF PROTO=UDP SPT=34003 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.16.70.106 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=51 ID=11105 DF PROTO=UDP SPT=39002 DPT=1047 LEN=24 MARK=0x800000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.255.6.34 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=47 ID=36497 DF PROTO=UDP SPT=53049 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.16.76.130 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=51 ID=3302 DF PROTO=UDP SPT=26457 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=50.7.114.59 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=53 ID=60346 DF PROTO=UDP SPT=34003 DPT=1047 LEN=24 MARK=0x8000000
May 5 19:18:00 kernel: DROP IN=eth0 OUT= MAC=0c:9d:92:ab:69:a0:00:01:5c:ab:62:46:08:00 SRC=198.16.70.106 DST=73.129.208.175 LEN=44 TOS=0x00 PREC=0x20 TTL=51 ID=11105 DF PROTO=UDP SPT=39002 DPT=1047 LEN=24 MARK=0x800000