When your mobile tether is active you might notice that your home router stops working properly. This is often due to IP address overlaps between devices. These conflicts happen because both devices are trying to manage network traffic. Sometimes they end up using overlapping gateway addresses, which causes IP address conflicts.

The first step in diagnosing this issue is to check your network settings. Look at the IP address range your router is using. Most home routers default to 192.168.2.x. Now check the IP range your phone is assigning when it acts as a hotspot. Many mobile carriers use identical 192.168.1.x configurations, which causes a direct conflict. If both devices are using the duplicate DHCP zone, your devices can't tell how to route packets, leading to intermittent outages.

Disconnect your phone’s hotspot and test your router’s performance. If it does, the problem is definitely related to the tether. Now reconnect the tether and check if any devices on your home network can no longer connect. Sometimes your phone will assign itself an overlapping default route, causing DHCP exhaustion. You can check this by looking at your device's network details on your computer or phone. Look for messages about limited connectivity.

Another common issue is double NAT. This occurs when your mobile tether acts as a router and your home router also acts as a router. This double layer can increase latency and hinder gaming and video calls that rely on port mapping. To fix this, you can try disabling NAT read more on hackmd.io your router. This turns your router into a passive hub and lets your phone handle network management. Alternatively, you can use the phone as your primary access point, though this may drain your phone’s battery faster.

Tweak your phone’s network sharing options. Some phones allow you to select a custom DHCP pool. If you're using a a crowded channel on your router, and your phone is using a conflicting frequency, signal degradation happens. Try switching your router to an auto-channel setting. You can use a network scanning tool to see which bands are overloaded.

Power cycle both devices. Sometimes a simple reboot clears up stuck DHCP leases. After restarting, reestablish connections incrementally. If the problem returns once the phone resumes routing, you've confirmed the conflict. The best long term solution is to set a unique private IP scheme. Try using 192.168.50.x, so it no longer overlaps with your phone's standard 192.168.42.x. This way, you avoid recurring IP collisions.