It is quite possible that you may need to use a return.
Seems as if you are checking an awful lot for that little chip that could to be rather honest every 20 seconds to see if your providers modem is hanging if it is hanging that much you surely have an issue on your hands. Often your providers modem has an ip from which you can access it and view a live status of your connection to see things like this. Makes me wonder if you are sure it is not a cable issue often times cat5 cables go bad and visibly you would never be able to tell that they are bad. There are tools that help test this the best is a TDR ususally quite expensive though. Anyhow other things that go bad are the coax cable end if you have cable not uncommon to have to replace this end after a few years of service. Happened rather often with my satellite dish as well years ago.
Anyhow cat5 cables are a culprit in a network issue more than you know get new cable and test also NIC cards are good for going bad as well what happens is they will work and not work and work and not work it will seem as if they are good to the average computer tech without extensive testing. The options are a plenty for troubleshooting your issue.
It is good practice to power cycle your modems and routers every so often just like your computer things hang from time to time you can automate this process daily if you wished with a nodemcu. That may help things as well with a relay.
Anyhow best of luck to you try and add some returns to your subs and see how you fair from there.
forlotto
Where I buy my ESP8266 boards from... (Banggood)