RF data modems (MoCA being of that family) can degrade if the receiving device is "overloaded" with a too-strong signal. This can happen with directly connected devices with no splitters, longer cable, etc. The overload causes a higher bit/frame error rate leading to more error-correcting retransmissions, and from that, lower net throughput.
Same thing can happen in some WiFi, e.g., putting a handheld very close to a WiFi router (like 1m or so).
In directly connected coax, one can put a low cost attenuator "pad" in the coax, or several. These come in 3, 6, 9, ... dB insertion loss.
Only when the signal gets rather weak should you see a big change in net speed.
If two independent MoCA pairings are on the same coax system, each should be on a different frequency area (MoCA signals are 10's of MHz wide). Some products will listen and to detect other systems and automatically choose a frequency. This often fails to do the right thing. Some products have an admin screen to manually choose the frequency. Sharing one frequency should work but, as in WiFi, that frequency gets time-shared and that reduces speeds on average.
Same thing can happen in some WiFi, e.g., putting a handheld very close to a WiFi router (like 1m or so).
In directly connected coax, one can put a low cost attenuator "pad" in the coax, or several. These come in 3, 6, 9, ... dB insertion loss.
Only when the signal gets rather weak should you see a big change in net speed.
If two independent MoCA pairings are on the same coax system, each should be on a different frequency area (MoCA signals are 10's of MHz wide). Some products will listen and to detect other systems and automatically choose a frequency. This often fails to do the right thing. Some products have an admin screen to manually choose the frequency. Sharing one frequency should work but, as in WiFi, that frequency gets time-shared and that reduces speeds on average.
