New install of Linux Mint 20.2 Cinnamon (5.0.4) has ~50% packet loss - Caused by router?

I have recently installed Linux Mint 20.2 Cinnamon (5.0.4) (Kernel 5.4.0-74-generic) on my desktop on a separate drive from a Windows 10 install. On Linux I noticed very inconsistent connections when trying to download updates (often failing) and slow web page loading. After looking through a few similar questions on StackExchange sites I have checked the following: - The problem persists with both WiFi and Ethernet, and different Ethernet cables - Disabling IPv6 makes no difference - The issue only appears in Linux, not Windows 10 (same machine) - There are **zero** dropped packets when using my tethered phone for internet - When running "ping 8.8.8.8 -c 30" (or 139.130.4.5, or 8.8.4.4) I get pretty consistent behavior where it "switches" on and off so that a few pings in a row return successfully, then the next few have "Destination Host Unreachable" errors (avg ~50% packet loss across multiple runs). Example: $ ping 8.8.8.8 -c 30 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. From 192.168.1.1 icmp_seq=1 Destination Host Unreachable From 192.168.1.1 icmp_seq=2 Destination Host Unreachable From 192.168.1.1 icmp_seq=3 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=4 ttl=113 time=36.8 ms 64 bytes from 8.8.8.8: icmp_seq=5 ttl=113 time=30.2 ms From 192.168.1.1 icmp_seq=6 Destination Host Unreachable From 192.168.1.1 icmp_seq=7 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=8 ttl=113 time=38.9 ms 64 bytes from 8.8.8.8: icmp_seq=9 ttl=113 time=28.9 ms From 192.168.1.1 icmp_seq=10 Destination Host Unreachable From 192.168.1.1 icmp_seq=11 Destination Host Unreachable From 192.168.1.1 icmp_seq=12 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=13 ttl=113 time=38.1 ms 64 bytes from 8.8.8.8: icmp_seq=14 ttl=113 time=40.5 ms From 192.168.1.1 icmp_seq=15 Destination Host Unreachable From 192.168.1.1 icmp_seq=16 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=17 ttl=113 time=32.7 ms 64 bytes from 8.8.8.8: icmp_seq=18 ttl=113 time=31.8 ms From 192.168.1.1 icmp_seq=19 Destination Host Unreachable From 192.168.1.1 icmp_seq=20 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=21 ttl=113 time=39.5 ms 64 bytes from 8.8.8.8: icmp_seq=22 ttl=113 time=34.2 ms From 192.168.1.1 icmp_seq=23 Destination Host Unreachable From 192.168.1.1 icmp_seq=24 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=25 ttl=113 time=51.0 ms 64 bytes from 8.8.8.8: icmp_seq=26 ttl=113 time=30.6 ms From 192.168.1.1 icmp_seq=27 Destination Host Unreachable From 192.168.1.1 icmp_seq=28 Destination Host Unreachable 64 bytes from 8.8.8.8: icmp_seq=29 ttl=113 time=48.8 ms 64 bytes from 8.8.8.8: icmp_seq=30 ttl=113 time=35.3 ms --- 8.8.8.8 ping statistics --- 30 packets transmitted, 14 received, +16 errors, 53.3333% packet loss, time 29275ms rtt min/avg/max/mdev = 28.926/36.946/50.983/6.365 ms Additionally, I noticed very similar behavior several months ago when I originally tried setting up a Linux install on a different computer (gave up and stuck with Windows). I thought that it was the physical network adapter since it had driver issues, but the new setup disputes that. It also doesn't seem to be dependent on the Linux version since I had similar issues with regular Ubuntu and Mint installs. All of this is pointing me towards the common factor of the router, which is an Orbi LTE LBR20 running off of a 4G signal (rural internet sucks). **My question is:** what can I do next to confirm the router as the culprit and is there a "simple" fix? Switching to another provider is difficult due to few options at this location and I don't think we're allowed to modify firmware since the router is provided with the internet service. Please let me know if you need more info. Edit 12/30/2021: adding Ethernet adapter info per request in comments: The driver was updated by downloading the latest R8125 driver from the manufacturer's website and installed using two methods: using the autorun.sh provided with the driver and using dkms per the instructions here: https://askubuntu.com/questions/1263363/2-5g-ethernet-linux-driver-r8125-installation-guide Both methods produced the same results. description: Ethernet interface product: RTL8125 2.5GbE Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:2a:00.0 logical name: enp42s0 version: 05 serial: d8:bb:c1:69:fd:c6 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8125 driverversion=9.007.01-NAPI duplex=full ip=192.168.1.40 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:37 ioport:f000(size=256) memory:fc500000-fc50ffff memory:fc510000-fc513fff Update 1/19/2022: I have been able to "bypass" the issue by using a computer running Windows 10 as a wifi-hotspot, then connecting to the hotspot in Linux. This works reasonably well since I get the expected speeds with good stability, but I'm not fond of chaining connections like this. Does this provide any hints as to why Linux is seeing issues, but not Windows 10? Could the same thing be accomplished with a modem/router instead of another PC?