Internet keeps disconnecting and modem restarts when the temperature gets too high.

My internet keeps getting disconnected at random times thorughout the day. This has been happening for the past 2 years every summer when the temperature starts to rise. The random disconnects stop around September -October when the temperatures go down.

I use an Arris SB6190 modem connected to one splitter. 

The problem, as far as I've been able to tell from my research, is the upstream connection. The power normally sits around 48-50dBmV, but right before it disconnects, it shows at over 51, with not all channels connecting. At that point, the modem usually resets. My understanding is that the modem is having trouble communicating with the Cox servers, so it needs to increase the signal strength.

Here's a normal status screenshot:

Downstream Bonded Channels
Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Corrected	Uncorrectables
1	Locked	256QAM	21	903.00 MHz	-3.10 dBmV	38.98 dB	496	3275
2	Locked	256QAM	1	783.00 MHz	-1.60 dBmV	40.37 dB	828	2078
3	Locked	256QAM	2	789.00 MHz	-1.80 dBmV	38.98 dB	700	3494
4	Locked	256QAM	3	795.00 MHz	-1.80 dBmV	38.98 dB	499	3196
5	Locked	256QAM	4	801.00 MHz	-1.90 dBmV	38.98 dB	810	2937
6	Locked	256QAM	5	807.00 MHz	-2.40 dBmV	38.98 dB	897	4145
7	Locked	256QAM	6	813.00 MHz	-2.40 dBmV	38.98 dB	900	4335
8	Locked	256QAM	7	819.00 MHz	-2.30 dBmV	38.98 dB	751	3009
9	Locked	256QAM	8	825.00 MHz	-2.60 dBmV	38.61 dB	569	3003
10	Locked	256QAM	9	831.00 MHz	-2.60 dBmV	38.98 dB	1168	4819
11	Locked	256QAM	10	837.00 MHz	-2.30 dBmV	40.37 dB	791	4238
12	Locked	256QAM	11	843.00 MHz	-2.40 dBmV	38.98 dB	500	3552
13	Locked	256QAM	12	849.00 MHz	-2.70 dBmV	38.61 dB	448	2269
14	Locked	256QAM	13	855.00 MHz	-2.60 dBmV	38.61 dB	680	5136
15	Locked	256QAM	14	861.00 MHz	-2.70 dBmV	38.98 dB	448	3262
16	Locked	256QAM	15	867.00 MHz	-2.90 dBmV	38.61 dB	616	4181
17	Locked	256QAM	16	873.00 MHz	-3.20 dBmV	38.61 dB	736	5289
18	Locked	256QAM	17	879.00 MHz	-3.20 dBmV	38.61 dB	531	3176
19	Locked	256QAM	18	885.00 MHz	-3.30 dBmV	38.61 dB	661	3012
20	Locked	256QAM	19	891.00 MHz	-3.20 dBmV	38.98 dB	386	2403
21	Locked	256QAM	20	897.00 MHz	-2.90 dBmV	38.61 dB	423	2282
22	Locked	256QAM	22	909.00 MHz	-3.40 dBmV	38.61 dB	458	3348
23	Locked	256QAM	23	915.00 MHz	-3.60 dBmV	37.64 dB	315	2342
24	Locked	256QAM	24	921.00 MHz	-3.30 dBmV	38.61 dB	440	2186
25	Locked	256QAM	25	927.00 MHz	-3.30 dBmV	38.20 dB	155	776
26	Locked	256QAM	26	933.00 MHz	-3.30 dBmV	38.20 dB	128	1305
27	Locked	256QAM	27	939.00 MHz	-2.90 dBmV	38.20 dB	129	1384
28	Locked	256QAM	28	945.00 MHz	-2.50 dBmV	38.20 dB	119	1342
29	Locked	256QAM	29	951.00 MHz	-2.50 dBmV	38.20 dB	140	1942
30	Locked	256QAM	30	957.00 MHz	-2.20 dBmV	38.20 dB	139	1341
31	Locked	256QAM	31	963.00 MHz	-2.00 dBmV	38.60 dB	157	1310
32	Locked	256QAM	32	969.00 MHz	-2.10 dBmV	38.20 dB	193	1358

Upstream Bonded Channels
Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	2	5120 kSym/s	23.50 MHz	49.00 dBmV
2	Locked	ATDMA	4	5120 kSym/s	36.30 MHz	49.00 dBmV
3	Locked	ATDMA	3	5120 kSym/s	29.90 MHz	49.50 dBmV
4	Locked	ATDMA	1	5120 kSym/s	16.90 MHz	49.00 dBmV

I've read about using a cable signal amplifier with active return, but before I start spending money on that, I wanted to see if I was on the right track, or if there are any othe suggestions.

Thanks