Core Issue
This issue is most likely caused by fragmentation of packets needed to pass traffic, but the Don't Fragment (DF) bit is set.
Resolution
Increase the Maximum Transmission Unit (MTU) to 1524 or use Policy-Based Routing (PBR) to clear and set the DF bit. Another option is to change the Transmission Control Protocol (TCP) Maximum Segment Size (MSS) option value on Synchronization (SYN) packets that traverse through the router.
For more information, refer to Why Can't I Browse the Internet when Using a GRE Tunnel?.
Destination
Multiple devices on different network
Source
Multiple devices
Source and Destination Physical Connectivity
Source and destination exist on different subnetwork
Connected over tunnel interface
