my modem/router is generating repeated T3 timeouts and MDD message timeouts

This has been happening for about 8 months. High ping spikes(300-1000+ms), packet lost while gaming. I had an ARRIS SBG10 modem/router combo that was maybe half a year old and I figured maybe that was the issue, So I bought a netgear nighthawk ac1900, and the issues persist. I bought a better coax cable and it was still the same. A tech came here and replaced the outside/wall wiring and nothing seem to fix this issue. They did mention that my modem/router wasn't connected even though I was receiving internet. They called in for me and connected it, even thought i already did it through the phone app.

Current Cable Modem is: Netgear Nighthawk AC1900 (C7000v2)

EVENT LOG:

2026-6-14, 23:43:54	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:43:35	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:08:52	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:08:47	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:08:02	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:08:01	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:01:20	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:01:14	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 23:00:29	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:59:41	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:54:32	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:54:23	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:53:32	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:53:21	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:17:21	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:17:19	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:16:02	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:15:54	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:10:55	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:10:52	Critical (3)	SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;
2026-6-14, 22:09:06	Warning (5)	MDD message timeout;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.0;

It does this all day long.

CABLE CONNECTION: (i reset my modem about 5 hours ago)

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	627000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Enabled	BPI+
IP Provisioning Mode	Honor MDD	honorMdd(4)

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	29	627000000 Hz	3.8 dBmV	31.9 dB	10637515	5559591
2	Locked	QAM256	13	531000000 Hz	4.3 dBmV	40.2 dB	0	0
3	Locked	QAM256	14	537000000 Hz	4.1 dBmV	40.4 dB	0	0
4	Locked	QAM256	15	543000000 Hz	4.3 dBmV	40.8 dB	0	0
5	Locked	QAM256	16	549000000 Hz	4.6 dBmV	40.9 dB	0	0
6	Locked	QAM256	17	555000000 Hz	4.5 dBmV	40.9 dB	0	0
7	Locked	QAM256	18	561000000 Hz	4 dBmV	40 dB	0	0
8	Locked	QAM256	19	567000000 Hz	4.9 dBmV	41.1 dB	0	0
9	Locked	QAM256	20	573000000 Hz	4.6 dBmV	40.7 dB	0	0
10	Locked	QAM256	21	579000000 Hz	4.3 dBmV	39.9 dB	2	0
11	Locked	QAM256	22	585000000 Hz	4.7 dBmV	40.6 dB	0	0
12	Locked	QAM256	23	591000000 Hz	4.1 dBmV	40.2 dB	2	0
13	Locked	QAM256	24	597000000 Hz	3.7 dBmV	40.1 dB	2	0
14	Locked	QAM256	25	603000000 Hz	4.2 dBmV	40.3 dB	1	0
15	Locked	QAM256	26	609000000 Hz	3.8 dBmV	40 dB	3	0
16	Locked	QAM256	27	615000000 Hz	3.5 dBmV	40.2 dB	3	0
17	Locked	QAM256	28	621000000 Hz	3.3 dBmV	39 dB	0	0
18	Locked	QAM256	30	633000000 Hz	2.8 dBmV	29.9 dB	0	0
19	Locked	QAM256	31	639000000 Hz	3.2 dBmV	32.7 dB	0	0
20	Locked	QAM256	32	645000000 Hz	2.7 dBmV	40.3 dB	0	0
21	Locked	QAM256	33	651000000 Hz	2.6 dBmV	39.9 dB	0	0
22	Locked	QAM256	34	657000000 Hz	2.7 dBmV	40.1 dB	0	0
23	Locked	QAM256	35	663000000 Hz	2.5 dBmV	39.9 dB	0	0
24	Locked	QAM256	36	669000000 Hz	2.1 dBmV	39.4 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	2	5120 Ksym/sec	16400000 Hz	46.3 dBmV
2	Locked	ATDMA	5	5120 Ksym/sec	35600000 Hz	44.5 dBmV
3	Locked	ATDMA	3	5120 Ksym/sec	22800000 Hz	45.3 dBmV
4	Locked	ATDMA	4	5120 Ksym/sec	29200000 Hz	45.5 dBmV
5	Locked	ATDMA	6	2560 Ksym/sec	40400000 Hz	44.8 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

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XfinityKei

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2.5K Messages

8 hours ago

@dreamielee Our team is here to help! Can you please direct message me your first and last name along with your full service address so I can look closer at those T3 timeouts to assist you further?
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dreamielee

my modem/router is generating repeated T3 timeouts and MDD message timeouts

XfinityKei

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