My 8620 printer constantly goes offline. I reinstalled the printer. It went offline again.

[---FSM]

My 8620 printer constantly goes offline.  I reinstalled it and it printed one job and then went offline, again.

[BeemerBiker]

The 8620e can operate in the 2.4 and the 5ghz band. I suspect the problem is the SSID of both bands (in the modem) is the same and the printer gets a different IP address when it wakes up from sleep depending on which band it is assigned by the modem.

Make the printer use only the 2.4ghz band. At the printers control panel look for the option to select 2.4, 5ghz or "auto" and select 2.4. If the printer does not have those options then you will have to log into the modem and rename one of the bands.

It might be simpler to access the printer control page and tell it to never sleep.

If using only only the 2.4ghz b and solves the problem then skip the next suggestion.

----
If you are comfortable with programming the modem, locate the printer in the modem (see below) and assign the IP4 address as fixed. When it wakes up from sleep it will get the exact same IP address. This actually has to be done in flex system. If you have multiple WiFi boosters then you have a flex system. 

A network or status printout will provide the IP and also a MAC address.  You lookup either address in the DHCP server list of the modem, and when you find it then set it to a fixed address.