Will the connection still ultimately go through the 4G Wifi modem?
If so then you are going to have to accept that depending on signal strength you will not always the best connection. Bottom line, if that's the best Internet connection you have then let it run and don't sweat the alerts from the pool. I'd also look at the Daily hashrate that Slush shows. That's a better average to gauge what's going on.
20 meters is a long run 10 meters to a switch to ten meters will help.
as for wifi it is hard to tell . where I am wifi drops out constantly as I am near a large military base with plenty of planes. They cause a lot of drop outs.
he has 1 issue for sure a 20 meter / 60 ft run is not that relaible and he is most likely compounding it with the wifi modem.
two of these
https://www.amazon.com/gp/product/B01ELMYN4Q/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1with this in-between
https://www.amazon.com/D-Link-Gigabit-Unmanaged-Desktop-DGS-108/dp/B000BCC0LO/ref=sr_1_1_sspa?would assure a solid signal to the wifi which could still drop out.
I like to keep wires at 30 feet or 10 meters and use low-cost switches to help boost signal.
router ---10 meter cable-- switch--- 10 meter cable--- switch--- lots of short cheap cables to the miners
If I do a really long run I use boosters like this
https://www.amazon.com/gp/product/B002CLKFTG/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1this is in a 350 foot run between 2 buildings and it stopped the dropouts.
(Moderator's note: This post was edited by frodocooper to remove multiple nested quotes.)