Cornerstone 1500 and SB6120

I am having some trouble using a DOCSIS 3.0 modem on my Arris 1500. DOCSIS 2.0 modems work fine in DOCSIS 1.1 mode.

When using the SB6120:

It registers fine, obtains ip address 10.5.5.100/24 and configuration file. A PC on the client side will also be able to obtain it's network settings from the DHCP server on the 10.5.5.0/24 network.

For a few seconds, or minutes, it seems to work fine.
From 10.5.5.0/24 network it will respond to pings and SNMP queries. (micro-reflections are reported as 0dB.
Fron the client side it will forward traffic, and respond to http requests at 10.5.5.100 and 192.168.100.1.
The CMTS reports it is working as DOCSIS 1.0 modem. (The SB5101 would be reported as working at DOCSIS 1.1 level.)

Then the modem goes bad:
From 10.5.5.0/24 network it appears to be dead. Does not respond to ping or SNMP query. CMTS thinks nothing is wrong with modem, even thoug the modem won't respond to a ping from the CMTS.
From client side it will respond to ping and respond to http requests at 10.5.5.100. But it does not forward traffic, and eventually stops answering http request at 192.168.100.1.

Actually it seems that a blast of upstream traffic triggers this.

My provisioning software (Incognito) lets me create the modem config file in the gui and then generates the binary, so I have no way of providing a txt version of my config file.

[cmts] remote2> putcfg display
1.3.6.1.2.1.1.5.0 OctetString "cmts" // sysname.0
1.3.6.1.2.1.69.1.3.1.0 IpAddress 10.5.5.11 // docsdevswserver.0
1.3.6.1.2.1.69.1.3.2.0 OctetString "CMTS_ALBUM_4.3.1" // docsdevswfilename.0
1.3.6.1.2.1.69.1.3.3.0 Integer 3 // docsdevswadminstatus.0
1.3.6.1.4.1.482.60.5.1.1.0 Integer 4 // lcprovisioningcontrol.0
1.3.6.1.4.1.482.60.5.1.2.0 IpAddress 10.5.5.243 // lcconfigipaddress.0
1.3.6.1.4.1.482.60.5.1.3.0 IpAddress 255.255.255.0 // lcconfigipsubnet.0
1.3.6.1.4.1.482.60.5.1.4.0 IpAddress 10.5.5.1 // lcconfigipgateway.0
1.3.6.1.4.1.482.60.5.1.5.0 IpAddress 10.5.5.11 // lcconfigtftpaddress.0
1.3.6.1.4.1.482.60.5.1.6.0 OctetString "firmware" // lcconfigtftpfilename.0
1.3.6.1.4.1.482.60.5.1.9.0 IpAddress 132.246.168.164 // lcconfigsntpaddress.0
1.3.6.1.2.1.10.127.1.1.1.1.2.3 Integer 123000000 // docsifdownchannelfrequency.3
1.3.6.1.2.1.10.127.1.1.1.1.4.3 Integer 4 // docsifdownchannelmodulation.3
1.3.6.1.2.1.2.2.1.7.2 Integer 1 // ifadminstatus.2
1.3.6.1.2.1.2.2.1.7.5 Integer 2 // ifadminstatus.5
1.3.6.1.2.1.2.2.1.7.6 Integer 2 // ifadminstatus.6
1.3.6.1.2.1.2.2.1.7.7 Integer 2 // ifadminstatus.7
1.3.6.1.2.1.2.2.1.7.8 Integer 2 // ifadminstatus.8
1.3.6.1.2.1.2.2.1.7.9 Integer 2 // ifadminstatus.9
1.3.6.1.2.1.2.2.1.7.10 Integer 2 // ifadminstatus.10
1.3.6.1.2.1.2.2.1.7.11 Integer 2 // ifadminstatus.11
1.3.6.1.2.1.31.1.1.1.18.2 OctetString "show" // ifalias.2
1.3.6.1.2.1.10.127.1.3.5.1.4.1.1 Integer 3 // docsifcmtsmodtype.1.1
1.3.6.1.2.1.10.127.1.3.5.1.4.1.2 Integer 3 // docsifcmtsmodtype.1.2
1.3.6.1.2.1.10.127.1.3.5.1.4.1.5 Integer 3 // docsifcmtsmodtype.1.5
1.3.6.1.2.1.10.127.1.3.5.1.4.1.6 Integer 3 // docsifcmtsmodtype.1.6
1.3.6.1.4.1.482.60.5.5.1.0 Integer 2 // lcforwardingmode.0
1.3.6.1.4.1.482.60.5.8.1.0 Integer 3 // lccmtsbootprelaycontrol.0
1.3.6.1.4.1.482.60.5.8.2.1.2.1 IpAddress 10.5.5.241 // lccmtsbootprelaysvrtargetip.1
1.3.6.1.4.1.482.60.5.8.2.1.5.1 Integer 1 // lccmtsbootprelayrowstatus.1
1.3.6.1.4.1.482.60.5.9.1.0 Integer 2 // lccmtsdnsresolvercontrol.0
1.3.6.1.4.1.482.60.5.9.5.1.2.1 IpAddress 206.47.244.101 // lccmtsdnsresolverserverip.1
1.3.6.1.4.1.482.60.5.9.5.1.5.1 Integer 1 // lccmtsdnsresolverrowstatus.1
1.3.6.1.4.1.482.60.7.13.0 Integer 2 // lcconcatenationenabled.0

putmng display
$ box
name "cmts"
$ admin
sw-server-ip-addr 10.5.5.11
sw-filename "CMTS_ALBUM_4.3.1"
sw-admin-status ignore-provisioning-upgrade
provisioning-control use-nvram
$ ip-level
config-ip-address 10.5.5.243
config-ip-subnet 255.255.255.0
config-ip-gateway 10.5.5.1
$ admin
config-tftp-ip-addr 10.5.5.11
config-tftp-filename "firmware"
time-sntp-addr 132.246.168.164
$ downstream
frequency 123000000
modulation qam256
$ cable-level
admin-status up
$ upstream-specific/5
admin-status down
$ upstream-specific/6
admin-status down
$ upstream-specific/7
admin-status down
$ upstream-specific/8
admin-status down
$ upstream-specific/9
admin-status down
$ upstream-specific/10
admin-status down
$ upstream-specific/11
admin-status down
$ cable-level
alias "show"
$ modulation/1/request
type qam16
$ modulation/1/data-request
type qam16
$ modulation/1/short-data
type qam16
$ modulation/1/long-data
type qam16
$ forwarder
forwarding-mode dhcp-arp
$ admin
bootp-relay-control relay-tagging-enabled
$ bootp-modify/1
server-ip-addr 10.5.5.241
status active
$ ip-level
dns-control enabled
$ dns-modify/1
server-ip-addr 206.47.244.101
status active
$ cable-level
concatenation-control disabled