CM2000 Modem and Router R7000 5ghz disconnects to the internet periodically. 2.4ghz does not.

[HAgrest]

I just intalled the CM2000 cable modem and since then the 5ghz wifi connection on my R7000 router stops connecting to the internet periodically.  I can switch to the 2.4ghz and connect to the internet while this is happening.  This problem did not occur before I switched modems.  My current ISP is Optimum.  

I tried switching the channel of the 5ghz connection but that did not seem to solve the problem.  Please help.

[plemans]

it might be coincidence with the modem switch. 

reason why is if the wired and 2.4ghz work fine, its not usually a connection to the modem, it tends to be a router issue. 

What actual version of firmware are you on with the R7000?

[HAgrest]

I am on version V1.0.9.88_10.2.88 for the R7000

[plemans]

Well there's newer versions and older versions. The newest is 1.0.11.116. 

the agreed upon older stable version is 1.0.9.42

I'd try upgrading and if it doesn't help, try the downgraded version. 

I'd recommend any firmware changes on the router been done over a hardwired connection, then do a factory reset, and clean install (not from a backup).