Inconsistent network speed

Hello all, I been having issues with my internet speed connection. I have Xfinity Comcast internet, 80Mbps download and 12Mbps upload. I have Netgear CM600 modem and using that with Netgear Nighthawk wireless router. I been trying different things with restarting the router, upgrading firmware on router etc., i would get correct speeds after router restart, but shortly after maybe 10 min later i get low speeds again. And it varies anywhere from 1Mbps to 80Mbps.

I use the testmy.net to test the internet speed and its very random i get anywhere in that range from 1Mbps to 80Mbps. I went out today and purchased a new linksys router for testing purposes so that i can see if the router is the issue, but i am getting the same internet speed drops on new router, which makes me think its the Cable modem thats causing the issue.

That said i have also tried restarting the cable modem as well and like with router restarts, the speed are ok for 10 min and they drop again. The cable modem shows all lights in green after restart. I also went in and copied the down and up stream channels perhaps someone can make better sense out of this. I am not sure how to interpret the signals bellow? Any help would be much appreciated.

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency	
609000000
 
Startup Procedure
Procedure	Status	Comment
Acquire Downstream Channel	609000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Enable	BPI+
IP Provisioning Mode	Honor MDD	IPv6 only
 
Downstream Bonded Channels
Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	16	609000000 Hz	-6.6 dBmV	36.5 dB	717	306
2	Locked	QAM256	1	519000000 Hz	-5.9 dBmV	36.2 dB	857	603
3	Locked	QAM256	2	525000000 Hz	-5.8 dBmV	37.8 dB	786	585
4	Locked	QAM256	3	531000000 Hz	-6.0 dBmV	37.9 dB	905	333
5	Locked	QAM256	4	537000000 Hz	-6.0 dBmV	37.7 dB	801	439
6	Locked	QAM256	5	543000000 Hz	-6.0 dBmV	37.6 dB	795	456
7	Locked	QAM256	6	549000000 Hz	-6.2 dBmV	34.8 dB	722	541
8	Locked	QAM256	7	555000000 Hz	-6.1 dBmV	36.5 dB	686	545
9	Locked	QAM256	8	561000000 Hz	-5.7 dBmV	34.1 dB	661	483
10	Locked	QAM256	9	567000000 Hz	-5.9 dBmV	34.8 dB	696	395
11	Locked	QAM256	10	573000000 Hz	-6.2 dBmV	30.9 dB	288866	89853
12	Locked	QAM256	11	579000000 Hz	-6.4 dBmV	33.9 dB	138318	1992
13	Locked	QAM256	12	585000000 Hz	-6.8 dBmV	37.2 dB	770	388
14	Locked	QAM256	13	591000000 Hz	-6.0 dBmV	37.3 dB	769	328
15	Locked	QAM256	14	597000000 Hz	-5.6 dBmV	37.3 dB	686	114
16	Locked	QAM256	15	603000000 Hz	-5.6 dBmV	32.6 dB	771	175
17	Locked	QAM256	17	615000000 Hz	-6.1 dBmV	33.4 dB	0	0
18	Locked	QAM256	18	621000000 Hz	-5.6 dBmV	32.0 dB	0	0
19	Locked	QAM256	19	627000000 Hz	-5.1 dBmV	37.9 dB	0	0
20	Locked	QAM256	20	633000000 Hz	-5.0 dBmV	38.1 dB	0	0
21	Locked	QAM256	21	639000000 Hz	-5.4 dBmV	37.8 dB	0	0
22	Locked	QAM256	22	645000000 Hz	-5.8 dBmV	36.7 dB	0	0
23	Locked	QAM256	23	651000000 Hz	-5.6 dBmV	25.6 dB	60	559
24	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
 
Upstream Bonded Channels
Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	65	5120 Ksym/sec	36400000 Hz	54.0 dBmV
2	Locked	ATDMA	66	5120 Ksym/sec	29500000 Hz	54.0 dBmV
3	Locked	ATDMA	67	5120 Ksym/sec	22600000 Hz	53.3 dBmV
4	Locked	ATDMA	68	5120 Ksym/sec	15700000 Hz	53.3 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 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

Thank you, Mike