Getting a web page with Javascript content

One of the items is a modem

Ahh - I actually had to do something like this with a ZTE MF730M dongle.

When I did what I described above I found that accessing this URL:

http://192.168.0.1/goform/goform_get_cmd_process?isTest=false&cmd=imei%2Chardware_version2Cmsisdn%2CLocalDomain%2Cwan_ipaddr%2Cipv6_wan_ipaddr%2Cppp_status%2Csim_imsi%2Crssi%2Crscp%2Clte_rsrp%2Cnetwork_type&multi_data=1

Got me all the data I needed as JSON.

Probably won't work for you, but worth a try :)