Slow Transfers - v1.27.5

Hello,

I am experiencing extremely slow transfers (around 20 kbps) when synchronizing between two remote clients (different ISPs).

All clients are v1.27.5. I have tested two local clients one a Synology DS1817+ running the SynoCommunity package, one running Unraid with Synching as a Docker container, the remote client is a computer running Windows 11.

Internally, the Synology and Unraid clients synchronize without an issue. Additionally, the Windows client is able to synchronize with other clients that are at that remote location (all on the same ISP), as well as other remote clients. For example:

Site A ↔ ISP 1 ↔ ISP 2 ↔ Site B (Slow Transfers) Site A ↔ ISP 1 ↔ ISP 2 ↔ Site C (Slow Transfers) Site B ↔ ISP 2 ↔ ISP 2 ↔ Site C (Transfers function as expected)

I have verified that port 22000 is open on the firewalls on all sites. Additionally, set host firewall rules to allow traffic on port 22000. I have tested with Relaying enabled and disabled, with no change.

Site A uses a pfSense firewall, but I have also tested with OPNsense, with no change. Sites B and C use Ubiquiti Dream Machine SEs.

Would welcome any thoughts or recommendations for troubleshooting.